The CWAL Rubber Room
"Hold on there. Nobody knows if happy = light! Sure, it feels that way, but there's no attitude-to-altitude conversion chart! For all we know, happiness can be like a very inert, heavy gas!"
... 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.