4e was when WotC discovered D&D has a very large problem - it’s not allowed to change anything, for worse or better.
This is true.
They're so close to discovering dice pool with advantage/disadvantage.
I started thinking about a 5e hack that converts the whole thing to a dice pool system. Instead of 1d20+X, it's Xd20. You can then have degree of success via "how many dice hit the number?" and degree of difficulty via "you have to hit X times"
There's a ton of other stuff I'd love to see changed. Mostly around the adventuring day and only-spellcasters-get-cool-stuff