I propose:
Skill based MMR that teaches you the game. Rank ups from graded red to green color scores for your class for the following stats:
Average distance from tank, based on spec, much looser for intentionally slow classes
Ability uptime, do you press buttons?
Total run time, relative to the dungeon benchmark
Total score is your best score of each type added together
Improve scores to move up difficulty tiers
Matchmade, ditch keys.
Make many many tiers, make the top like 20 out of 100 tiers impossible. Let people bite into it forever, strategize, get world firsts.
ilvl-less, fixed stat balance tiers manually done for each dungeon and tier each season. Can do it all once and set it and forget it, no more garbage nonsense bugs and broken crap for long periods of time. Just play in the range you can actually do and stop harassing people with purchased scores. Are a few people going to buy pilots? Yes, but it will be like 1% as many.
And from my other recent dungeon post:
What if, they split the queue like BG? Make single lane dungeons the dungeon queue, and have multilane dungeons be the epic dungeon queue.
If the game is actually fun to play for people, they will play it more. This system would be played like nothing WoW has ever seen.