The CWAL Rubber Room
"You know, it's easy for us to judge The Confederacy. The worst most of you have experienced so far as invasion goes is that some zealot won't stop telling you about Auir. But Mar Sara is the largest zerg corridor in the sector, and their invasion problems are on the order of magnitude of a full scale war between local magistrates and evil alien cerebrates who like to kill for reputation." - Inconsequential Lurker
Maybe gimme like 10-20 levels max if each one unlocks a substantial new ability that I'm actually going to notice but otherwise just let me play the damn game and stop making me pause to invest arbitrary tokens in incremental improvements that I won't even notice because the monsters get more powerful anyway.
Mass Effect 3 has the best progression mechanics and everything more complicated is just annoying busywork.
... no tangible payoff. Like, building Lulu as a strength fighter isn't really something anyone's going to do without a LOT of time and effort invested, and I'm not sure catering to that edge case is worth the quality of life issues you can introduce for the 99.9% of people who don't do that.
Also tbh, you can do some pretty interesting playstyle customisation with a good equipment system without adding too much complexity or asking too much commitment from your players if they want to go a little off-script.