WoW is a big house with lots of things to do and a lot of different player types with myriad possible goals.
one possible way to play the game is to just chill and relax. progression content is usually not designed to be relaxing. to progress, there must be challenge. with challenge comes frustration - the opposite of relaxation.
to me, the biggest problem to M+ progression right now is the lack of a learning on ramp.
we effectively jump right into a former +12 that has mechanics and affixes right away. no longer, do you have the previous m2-9 pathway of learning.
in the current mode, you can use m0 to learn mechanics without a timer and, one might argue, no stress.
HOWEVER, running and rerunning m0 to learn content provides no progression - no sense of improving.
of course, m+ is a grind of the same content. the same 8 dungeons over and over for months.
that is (more or less) fine if you feel like you are progressing the whole time.
but are you really going to want to run m0 nine times in each dungeon with no real benefit?
if you ran up to level 8 delves, you probably need nothing from m0.
at least in the old system, you started earning a new gear track and an io score at m2.
if we had the old m2-9 track again, then the delve progression could be scaled to that.
people who don’t want to run m+ can earn m+ gear up to the +9 range.
people who want to run M+ can have the former method of progression.
there will always be really good players who don’t need an m+ on ramp. but I think that there are many, many more who do.
in the previous system, the swirlies increased over time, their consequences increased over time, and you had time to learn them without instantly bricking a key.
a side note, I think the timers are pretty tight on some of these keys. two wipes should not brick a +4.