OK. So this is my opinion :
Homogenization to that degree is not the way to go in my opinion. The way forward is normalization.
And the coolest solution (in my opinion) is two fold :
FIRST : to accept the fact that there will ALWAYS be a meta comp.
So by abandoning the idea that by balancing throughput you can make for a more balanced and fun gameplay for all, you accept the fact that its an impossible task. Because it is.
Assuming that blizzard did a mathematically perfect tuning, where ALL classes do exactly the same DPS/HPS/tank… then… the meta would be governed by raid buff synergy and utility.
If on the other hand they do a lousy job and there is 1 or 2 OP specs, then the meta will be the utility and raid buffs that those specs are missing.
So. What to do?
So you dont need to give ALL utility to EVERYONE. Just to instead of trying to give something unique to everyone, you group them up and spread them. What would make a spec unique would be a specific permutation of a group of buffs. And HOW they are applied.
Shamans for example have Ancestral Vigor. Which offers DOUBLE the stamina of a priest Fortitude, except that fortitude is permanent, while Vigor needs to be maintained constantly via riptides.
However. Priest have fortitude by default, while Shamans need to spend 2 talent points. THAT is something that can be normalized.
With changes like these you don’t homogenize. But you normalize. Which is a different concept. And by doing so, you allow for more varied comps because you will have multiple combinations of classes that give you the “meta” buffs you want.
AND maintaining the unique flavor of each spec.
SECOND : Dungeon design.
I think that the 1-shot/healer DPS dilemma needs to stop.
Right now, dungeon scaling is for both damage and health of mobs. And eventually there must be a limit where its mathematically impossible to time keys. That is the purpose of scaling.
But. For the past 12 years there has been 2 fields : (A) The “limit” is mob HP (DPS). Like it was for most of SL. OR, (B) the “limit” is player HP (survivability).
In scenario one you promote offensive utility. In scenario 2 you promote defensive utility. And a “balance” is unachievable. Impossible to apply for each and every pull. You always end up in extreme cases of either scenario. Never somewhere in the middle.
So blizzard has to force artificially this “middle” ground. One way to do it, is to limit the damage to a maximum value.
So it scales as intended, to the point where things almost 1-shot you. But not quite. But after that, future key levels scale mob HP by DOUBLE the amount, to compensate no further damage scaling.
You will then end up with dungeons where you are barely alive, where you have to use all deff CDs on time, and your healer is busy healing. BUT, you ON TOP have to provide maximum DPS.
And this gives more value to balancing specs based on performance. Because performance will be something that matters.
And this is my super lengthy parragraph on what I think about your suggestion : I dont like homogenization. But I like normalization.