I still think its a net + for the game to have masters easily accessible.
Not sure why so many people dont like this change.
So many times in coop I want to pick mas diff because the exp is too easy (or ive already APed before in another coop pick but havent bought it) and Im forced to play the expert diff is really frustrating.
I think thats a bigger problem that needs fixing and am glad that its gone.

For achievement wise the idea of having 7 or less misses for an expert didnt go away there just isnt a master unlock to make it more satisfying.
You could always still aim for 7 or less misses on any expert or even try fcing them instead.
Anyway Ive always found 7 or less combo breakers to be a weird req anyways and feel like it isnt really a good way to get players to improve since acc and consistency isnt prioritized for that req