Because self improvement is actually rarely what the forums are about. On the surface they are, but in action they aren't.
Both sites would be focusing on prioritizing rewards for those who contribute to the self improvement categories (they try with the contributor banners but y'know) and neutralize the other categories. But it wouldn't make sense to do this. It stems mainly from the history of these kinds of forums. Looksmaxxing stems from incel culture, and in incel culture there isn't an objective/goal, it's just a community. So when they branch off into new communities, their end goal is still community over an objective/goal.
When you join a forum to talk about a product you use (like a game or service), or something like that, why do you think people join? It's to talk about that product. The off topic categories are normally inactive and when they are active they're normally respectful and still somewhat related to the primary subject at hand. Because the forum's objective is to facilitate discussion about that product or service, and people will use it as such.
Self improvement is kind of subjective and is hard and there isn't really a unified goal. So when you join a forum for self improvement, you're already starting on a weird foot. When you find out those forums most active categories are the off topic categories, where most of the rewards are for post count and not quality, where there's little penalty for making shit content, and when the forum's primary goal is community not a specific result, then it makes sense why nobody talks about self improvement.
I think if .org removed the special colors for post counts, made it where off topic posts didn't contribute to a user's rep count, requiring a minimum character count in certain categories, remove a lot of the profile cosmetics, etc., do you think people would use it the same? Not really.
With that being said, these sites are not self improvement forums, and you've been mislead if you think they are. They're blackpilled forums, where the main conversation is about how your appearance relates to how you are treated; they're not based solely off of your appearance, or it would be a beauty or a fashion or whatever forum.
Blackpill ideology is inherently miserable.