Okay, so to answer your questions, some understanding is needed.
The design intent is that the Great Vault represents the weekly reward for a given content lane. To assess, we need to consider the content relative to the lane a bit
Raids tend to be VERY static in design. If a raid were to drop ilvl 500 gear at heroic, then that raid is mostly tuned around 1.5 content tiers lower. In DF, that’s 13*1.5, or roughly -20 ilvl. So a heroic raid that drops 500 ilvl is typically going to be tuned roughly such that a reasonably competent (note, not elite/RWF) group of players could potentially progress the entire raid with no upgrades given enough time. While the content awards ilvl 500 here, the content really starts PRIOR to the end reward, thus each drop you get is higher than required for the target content, typically by a hefty jump. The weekly reward from GV is a guaranteed item that ALSO reflects that jump. As you get upgrades in this content lane, the content gets easier and easier; gear NERFS the content because raids are static in difficulty. In raids, gearing serves to make the content easier for players to compensate for lack of skill and/or coordination. Hence the phrase “gear is a crutch”
In M+, the content is ever scaling. The higher you progress, the harder and harder the content is. Objectively, M+ content will ALWAYS end up EVENTUALLY being the hardest content in the game. Gear in this content lane serves to get you to where this content lane ACTUALLY starts, ie, as you get gear in the M+ content lane, you’re catching UP TO the baseline for the content rather than playing at it. In terms of gear, M+ is the ONLY content lane where the end game doesn’t ACTUALLY start until gearing is min/max, and ironically, the only content lane that doesn’t reward max level gear from the content itself.
So we don’t see “raid == raid” and “M+ plus ilvl > raid” but rather “M+ plus ilvl <= raid”, where the respective difficulties are normalized by the content itself.
This means that, for raiders, they are getting a guaranteed piece ABOVE the ilvl needed for that content AND some RNG number of pieces above the ilvl needed along the way". For M+, you have more time cost per piece in the content lane, an additional penalty for failing the content in the lane, variable content difficulty in a given tier starting at jump and amplified at 7+ now, BUT in exchange you can farm gear.
In real world time, this basically just means you can trade time efficiency for gearing and/or easier slot filling BUT can bump your gear earlier IRL. In practice, the players capable of doing this for hero pieces and above are players who aren’t typically having issues in any content lane.
With this said, the idea behind the GV is that the reward represents the TARGET. For anything below mythic raiding and end game M+, this is easier/net positive for raiding, relative to time and comparable content levels. For the end game of each lane, this means Mythic raiding gets a better rate of loot progression until they hit a wall boss. For M+, this means that it takes a good handful of weeks to have sufficient gear to START the end game content at any meaningful level.
In terms of gear, there really shouldn’t exist such a disparity when M+ will objectively be the highest content at some point, yet has no loot mechanism to reflect that at parity.
M+ has improved, but this gap is still a penalty due to Blizzard trying to artificially make mythic raiding prestigious rather than a roster boss.
If M+ were to drop the highest loot like the other lanes, then much of the talent in the raiding scene flocks to it. They could gate M+ to avoid that, but then M+ does as a content lane.
Instead, the issue is that M+ doesn’t get the end game because it’s farmable, but raiding…isn’t farmable for whatever reason. The usual argument has been gating content for health reasons but for the average player, it doesn’t really matter. If you don’t sweat a little, having endless farming typically doesn’t change your play much.
Raiding needs to quit treating Mythic raiding as a special case, first. It’s not intuitive to have three tiers of the same content behaving one way, and then one tier behaving in an entirely different and counterintuitive way.
Once the design flaw of raiding itself is addressed, then we need to just permit raiding to be farmable in some metric. Even if it was just a “after killing N bosses in an N boss raid, your loot lockout resets” to encourage people to stick around to help others as needed.
And then, make the M+ crest/drops reflect what’s needed to upgrade the gear that drops, if only for simplification. Rather than needing to know that a 6 drops aspects before you need them to upgrade the gear that doesn’t drop until a 7, it’s just cleaner to have both breakpoints be either 6 or 7. And then, pick some point in the curve to permit Myth track as end of dungeon rewards. Even if it’s high into the curve, anyone playing at this level would easily be stepping to a mythic raid cadence until the season is dead anyway, and if RWF really wants to hyperfarm max ilvl gear…they could just make RWF a tournament realm like they do for the other content lanes
Basically, EVERY remaining pain points of the modern WoW gearing system are a symptom extending from the artificial logistic hurdles out into place to make Mythic raiding seem more special than it is. Great for streaming, terrible for everyone else