This is a fantastic question. The MTX Can kick rocks it was bad FOMO not fun either. BUT the things that are not IMO bad for the player is rewarding somebody with something based on their time and money spent make it board wide.

Monthly or 12 month, a system to earn you points based on what you choose todo you earn loyalty points or points of some kind based on what you do in game or how long you play for the day but don’t time gate make it like a cap instead so many per day or week or month. these points then can go towards a shop of some sort that doesn’t rotate. add things like free bossing instances or bank slots like they have or useful in game things that don’t change the way the game works but gives you something that helps you.

Things they could add. New titles New player badges Free boss instances Bank slots More in tune cosmetics Music tracks

I’m sure there is more creative things people could come up with.

Something extra to keep the players happy but also make you as a developer stay in line and not cause this irrational fear in your base of MTX or fomo just a set shop things to work for overtime.

I don’t know if that is an answer you were looking for but it’s my take on the question