Just like how Blizzard let us put any single set bonus on a Shoulder slot.
They should let us place any one rune to our weapon, no matter what slot it’s from.
Broken? Maybe. But the builds are getting kinda stale, and this would be fun. The same way these shoulder set-bonuses are fun.
Imagine all these builds we could try if we could keep that “must have” build-making Rune in our weapon and use some lesser, more utility focused runes.
Hybrids and classes that only have 1 option per rune slot for each role, tank/heal/dps would see 0 reason or benefit for their preferred role to use a weapon rune
Paladin, Shaman and Druid would all basically shrug and have to watch the other classes get fun new toys
Unless more runes were added to slots to help compensate it would be very unfair to anyone without a meaningful choice or gain
Could I get a Feral stun rune so I too can wield a Skillherald MoM?
This same argument applies more-so to shoulder runes. Fire Mage was very unexcited for the shoulder runes as most of their set bonuses did not have any meaningful gains or choices. In our pre-raid gear we were using elementalist which was a completely passive 2.5% DPS gain, and right now we use Igniter which is also has zero playstyle modification and gives 4-5% DPS gain but only because the interaction with Seal and 6-pc in Naxx. Very sad.
As far as hybrids, what you said is mostly just not true.
Paladin do not just have to shrug. Rets and Prot have multiple slots where they would like to take multiple options, as currently they have flip-flop the rune on an as-needed basis. I think only Holy is a bit bored, as Aura mastery is probably the only good option you could take which is a very situational gain.
I believe Boomkin would have to take a utility option, probably the absolute worst case scenario of any spec, but both Bear and Cat see DPS/rotation gains with Feral Sunfire on top of Mangle.
All Shaman specs gain a performance boost to their role.
Tank Rogue would be thrilled and DPS Rogue would also be very happy obviously.
Not going through all classes but most pure DPS would enjoy DPS runes, all Priest specs have rune choices, etc.
You would only need to add a rune for a very select few number of specs. Boomkin, HPal, and I’ve maybe missed a spec here or there.
only slot for ret/prot i can think of any choice is our legs runes which is either tremor totem or an interrupt and I cant think of any fight in PVE that requires both
no paladin runes options would increase dps for Ret, i can see prot making use of the dps runes but no ret would really benefit from the holy/prot runes
Wut?
Ret would like to take both Purifying Power and Improved Hammer of Wrath. Not only that, Ret would also like to take both Wrath and Fanaticism.
Prot currently alternates between Shield of the Righteous and Righteous Vengeance, as well as alternates between Hammer of the Righteous and Purifying Power. Prot would also love to be able to take Sheath of Light and Malleable Protection. Having both Art of War and Guarded by the Light would be nice in dungeons but not really that big of a gain I imagine.
There is so much overlap. Both Ret and Prot would love a wild card choice.
Hammer of wrath is a dps loss when used and with world buffs you’re already above effective crit cap so fanaticism is kind of nothing functionally
Between Martyr and Crusader Strike I never have mana issues unless im using the terrible 4pc T3 set for aoe
none of these options add any thing noteworthy or of meaning
Prot would eat for sure but as a ret the options are very sad
Mele hunter would do expose weakness. Boring but powerful. And we would still have f all cleave without swapping very good single targer runes for it.
Ranger hunter would have rapid fire + load n load. Probably.
Any fight that forced us out of melee range for periods of time would see a DPS gain from Improved Hammer of Wrath. Additionally, new tier bonuses could shape up our action economy - it’s hard to imagine they kill seal twisting as a build but something that gave you back extra GCDs, let’s say using Crusader Strike granting you the benefit of seal of martyrdom or something like that, you might find gaps in the rotation you could squeeze them in.
I should clarify that I play exo and have little experience and knowledge about twisting
but for exo none of the runes do anything useful or interesting
Might not be possible.
I say this because I think gear has 'enchantment hardpoint’s that can be used to apply boons to them.
We see them as: Sharpening Stones, Oils, Enchantment, Armor Kits, etc.
Weapons we know have 2 hardpoints; you can enchant them and then apply a temporary boon like Poisons, Windfury, Sharpening/Weighted stones, etc.
Armor, though, you can’t stack Armor Kits with Enchantments. But. I think you could in the early days. So it’s possible every item has 2 hardpoints.
[Shoulder] Glyphs and Runes take up one of those hardpoints. Meaning any item that already has those 2 hard points used, will not be able to support a 3rd boon.
as a pally that fuggin loves to try to play shockadin… i support this… so i can keep my exodin runes and slap Shock and Awe on my weapon, and thus finally making my fav meme specc viable again
Just do it on the neck then.
Warriors could get windfury for weapon rune
I’d like a Neck Rune to be something crazy.
…like maybe an entire Set Piece bonus.
Imagine being able to run two full Tier Sets worth of bonuses PLUS the shoulder single ‘line’ bonus.
That sounds boring for Fire Mage. Fire Mage would rather have a wild card rune than more set stuff. Tier sets 1 through 2.5 have done almost nothing for Mage because Mage was already strong and they didn’t want to scale them further. Giving us more of these… 
I’d like to see a Weapon rune be cosmetic in nature. Something like the Molten effect from MC, or the Shadow effect from BWL. Was a shame Naxx didn’t have a cool glow like previous hard modes.
Or hey, just make it so we can “rune” a different weapon appearance like a mini transmog for the weapon slot.
My response was because the OP said: “They should let us place any one rune to our weapon, no matter what slot it’s from.”
But that being limited to ‘just the Runes we have’ really doesn’t change anything for a class.
So it’s really not ‘cool’ it’s just like the Ring Runes; kind of “eh”.
Especially for the classes that already had a lot of abilities in Vanilla. Like, I purposefully go with the passive runes on my Warrior because I straight up don’t have the bar space to put active abilities and still easily reach them - I’d have to mouse-click them ( 
).
Well Blizzard should also give at least one final pass to the runes that basically never get used to buff em up a bit.
I can name an easy 4 runes on Warlock that no one ever uses.
Yep…classes with decent actives should have Runes that morph existing abilities.
Like Saber Slash would morph Sinister Strike; Crimson Tempest would morph Rupture to be an AOE bleed; Spellfire would morph Fireball; Spellfrost would morph Frostbolt; Frostfire would morph both Fireball and Frostbolt; Quick Strike would morph Heroic Strike. - Just to name a few.
But classes like Paladin and Shaman, which didn’t have a lot of active abilities to use and mainly just auto-attacked would keep most of their current Runes that add new abilities.
However, like I said, getting ‘one extra Rune ability’ is kind of “meh”.
Note: I’d also say they need to make a second pass at Tier bonuses…the Warrior one that allows you to use ‘previous stance’ abilities is just stupid; what warrior has spare space on their bar to place an ability from another stance. - I already had to do some macro-Foo to have Revenge/Overpower/Whirlwind work with Heroic Strike/Cleave. Specifically because I don’t have anymore ‘easy to reach’ keys to bind to bar slots.