M+ loot has to be limited because the dungeons are infinitely spammable and if they are rewarding, people will spam them like crazy, get geared, burn themselves out and cancel sub. So this is not an option.
Here is an option:
Remove the weekly vault.
The first 8 M+ dungeons you do in a week are guaranteed to drop 2-3 items for you. All keys you do after that don’t drop anything, except maybe valor points.
You do 8 dungeons and you’re done with loot for the week. Enjoy the ~20 pieces. After that, you can push your key, get it ready for much higher loot next week, practice more runs, chase rio… or hop on an alt.
Players will know after 8 dungeons, they are DONE with the loot. They won’t have loot expectations, so running dungeons won’t result in disappointment.
Players will be free to help weaker players, because doing lower keys won’t degrade their chests and they won’t feel like they’re missing out on a chance to get better loot by not running an M+15 key.
Of course, players who don’t want to play won’t feel pressured to spend hours farming and getting disappointed and they’ll be free to play other games and come back to WoW next week. They won’t burn out, they will stay subbed for longer.
With valor points coming back, we can have dungeons drop infinite valor points, to speed up gearing and give players who want to continue pursuing progression a non-rng based path towards it.
If players are pursuing a very specific bis from a very specific dungeon, they can try to have their first 8 runs be just that dungeon and greatly boost their chance of getting the item they want.