The idea behind M+ is awesome, and it’s great giving people an alternative for end game gear/power progression. That said, it’s poorly implemented. Blizz stated they wanted M+ to be looked at as an alternative to raiding. That’s good. The problem is that due to the scaling of gear per patch/tier increase, many things in m+ will always remain BiS. When you can endlessly spam 1 dungeon to go for that gear, it’s just that much more lucrative. In Legion it also had the benefit of being the fastest and easiest way to gain AP.
I’ve always thought that Blizz should implement a level scaling similar to what they did for PvE gear in PvP instanced content. As an example: 410 ilvl piece from raid would remain 410 in raids, regular/heroic/mythic dungeons, and open world, but would be downgraded to roughly 370 ilvl in PvP and m+. The reverse also holds true, where m+ downgrades in raids and PvP, as well as PvP gear downgrading in raids and m+. Simple change that makes these concepts in the game truly become separate entities that favors the player interested in doing those things.
Some players might be interested in all those aspects. That’s fine. Allow players optional bag purchases that have 50 slots but can only contain armor/weapon pieces so they have extra slots to carry around different gear sets.
Possibly not the best idea, but short of putting up an instance lock to cap how lany m+ you can run or how many loot chances you get, I can’t think of a better fix.