I am so glad that you asked! 
The point of the whole “stat stick” Legendaries idea is balance. Regular affixes need to be well balanced amongst themselves in any case. Legendary powers need to be balanced against each other in any case. The hardest and most crucial part, however, is balancing Legendaries that play out their power in gameplay situations not readily quantifiable against the number crunch of regular item affixes. This is where I feel “stat stick” Legendaries instead of endgame viable Magic and Rare items could help.
Maybe I am really freaking out over nothing here, please help me see the obvious if I don’t. In my perception, the balance between Legendary powers and regular affixes is at the root of what divides the community: Some really want to play with exciting Legendaries and are afraid that uninspiring stat stick builds will dominate thanks to Magic and Rare items. The other bunch of us fiercely defend the endgame viability of Magic and Rare Items because we do not want to end up being shoehorned into predesigned builds and gameplay patterns by Legendaries so powerful that they are essential to compete. Blizzard absolutely needs to get the balance between regular item affixes and Legendary Powers right.
How do “stat stick” Legendaries help balance? They bring competition between regular affixes and Legendary powers to the same gear slot. In fact, even down to a single “special power” affix in that gear slot, since in this system as I think of it at the moment, all endgame viable items would roll the same number of regular affixes with the same maximum roll. The only thing that differentiates their power potential is the respective special power affix (Legendary, Unique and new “stat stick” powers that simply double down on the potency of regular affixes). Now, instead of having to balance legendary powers and regular affixes separately, you can easily measure them against each other directly in real-game situations by only swapping out one item. I know I probably make this sound easier than it will be, since I for one at least want to allow Legendary powers to chain link their gameplay effects together in interesting ways to achieve their real power potential (which should be capped at a similar level, of course, of what other more granular single-slot powers would achieve altogether for the same number of slots required).
Looking at the alternative, balancing Magic and Rare Items to be endgame viable seems much more daunting to me. If we assume 10 item slots, we have already 66 different possible combinations between blue, yellow and orange alone. Each item tier combination has a different total max regular affix roll to compare with a different number of Legendary Powers you must give up on in order to achieve it. Since the number of affixes is not the same either for each combination, either, you must account for different additional affixes chosen on a Rare or sacrificed on a Magic Item, further multiplying the scenarios. Sure, the regular affixes can and should be separately balanced against each other so that quantitatively you can assume each roll has equivalent “power potential.” But numbers quickly gain and lose meaning in very specific, dynamic and context-dependend gameplay situations. Maybe game balancing experts just shrug at this mess and get on with it. Being a complete noob myself, I would think that in the end, there really is no alternative to playtesting all potential combinations in adequately sampled gameplay situations. If resources are scarce, I fear that they would rather be spent to balance out exciting Legendary powers instead of making sure that regular affixes remain powerful enough, which I feel is the most crucial balance to ensure build diversity.
Maybe I overestimate the balancing problem and Blizzard can pull it off. After all, Legendary powers will be in the hundreds and yield a vast number of combinations as well. Maybe it is sufficient to only playtest some builds fully equipped in Rares, make sure they do not fall off too far behind, and have very few handcrafted situations where Magic items actually matter in endgame. Maybe instead of “stat stick” Legendaries that come with their own problems, you prefer a “Legacy of Dreams” power that forces you to only equip Magic and Rares in return for a generic power boost that brings you up on par with Legendary builds, that should be easy enough to balance. Maybe you are confident that a sufficient number of more generic Legendary Powers will be available in the game anyways, so that decking yourself out exclusively with Legendaries of that kind will not restrict build diversity in any significant way. I would appreciate to hear everybody’s thoughts on that.
I agree, prefer rarer and less random drops as well. Not sure though which part of the system sketched out in my Devil’s Advocate post suggests more frequent excitement with subsequent frustration to you, could you clarify? Yes, Legendaries would be more random and need longer to roll perfectly, since they basically have to live up to what Rares are in the Dec 2020 system. Here drop rates for Legendaries needs to be higher compared to usefulness, so that you get Legendary Essences for much less random Rares which become a transitional tier in the vertical item progression. Legendaries essentially become our current idea of endgame Rares. I don’t particularly like that system either, but believe it could potentially alleviate balancing. Worst thing that can happen is that build choice is limited by an itemization which fails to balance for “regular affix” type powers to be relevant at endgame.
Wrong. What the Dec 2020 Update said is that Uniques would have “heavily thematic and usually class-specific powers.” There is no generic / specific power distinction visible to me at all. Check out the Legendary Ring of Three Curses shown in the same blog post: “Meteor gains a 45% critical strike damage bonus against vulnerable targets”). That seems fairly skill specific and not generic to me, and as others have mentioned, we have seen many similar examples of skill- and class-specific Legendaries.
Actually, your mentioning of Uniques caused me to read up on them again only to find out that I myself also had a misconception of how they were presented to us. I sort of assumed because Uniques replaced Mythics, they would also be the most powerful items in the game, but come with the same restriction in that you can only equip one at a time. Reading back, I think that was probably not their intention. Blizzard said that the player could focus on (various?) “skills augmented by Uniques we designed”, which at least implies they mean for you to equip various Uniques at a time.
Whether a Unique’s regular and legendary affixes would be more powerful than Legendaries is not really clear in the blog post either. From comparable max life and stat rolls on Unique and Legendary items showcased, it would seem that they are at roughly the same level. That would be coherent with the statement that they deleted Mythics because “we don’t want to create an item quality that invalidates all others”, although Mythics really only could invalidate one slot at a time.
As far as I can tell, the only clearly communicated design feature about Uniques is that they would be heavily thematic “build-around items” that “always appear with the same affixes.” Have we had any further “hard evidence” (of fluid in development content, lol) regarding Blizzard’s concept of Uniques? I would be glad if you pointed that out to me.
Personally, I think I would design Uniques as “build-around items”. Clearly stronger than the average Legendary but balanced by only being able to equip one at a time. Fixed rolls point you to the direction to build for, but their true power doesn’t shine until you complement the Unique power with additional specific regular affix rolls required on your other gear slots. Once fully complemented, they should be stronger than the average Legendary but obviously only by a reasonable margin that does not invalidate builds without a Unique.
Yes, it seems that regular affix power on Uniques as per Dec 2020 were roughly the same as on Legendaries, thus below Rares and Magic items. As stated above, however, I am unsure whether the item tier system mixing in blues and yellows for stat boosts can really be a thing in D4, balance-wise. What’s your take on the problem?
Indeed the potential power for all endgame viable item types should be roughly the same. Those harder to come by, gear for or play around should be a tad stronger IMO, so long as they do not invalidate build choices that prefer not to use these types of items.
Exactly, I think a lot of us have the same concern. We need to have a way to create our own build as free as possible. Legendary powers akin to the current regular item affixes could be a solution, if they do not have crazy powers designed for your build, you could still equip those and be endgame viable.
Not sure what you mean by “what they are”. Legendaries in D4 have completely random affix rolls as of the current design, they even can randomly roll for different gear slots. The power seems to be rather fixed and static, and not reroll when you transfer it via essences iirc.
Uniques contrast with this design in that they drop for specific item slots and always with the same affix types, though probably random rolls on each predefined affix I guess.