The overwhelming majority of house rules I've seen posted in that subforum don't actually solve any problems. Many just overcomplicate things under the guise of adding realism or "fixing" a problem. I'd say a good portion of houseruling comes from folks who just want to say they came up with something.
There probably is some ego involved most of the time, but I think it's a mistake to think of game tinkerers as gamers who just want the gamer cred of writing something. There are easier ways to get that cred, starting with simple one-shot adventures.
I'm a frequent tinkerer myself; I've written many bad house rules, and a few good ones. My driving motivation is "This game doesn't work the way I want it to work," as well as the sheer enjoyment I get out of the very process of tinkering with rules. The second one just as much as the first; for example, there's a long list of problems I have with the 3e family of games. (My 2e list is longer.) Literally every time I scroll over the Paizo forums, I see thread titles that make me think "I'm so glad I don't have to deal with that anymore!" Because I have 4e, which plays like a dream. So all those arguments about optimizing and Stormwind, alignment, paladins, broken classes...they're total non-issues for me, because I finally have an edition of D&D that I don't have to butcher to have something that I'm really excited to run.
...And despite all that, I'm working on a 3e-spin-off game that works as I want 3.x to work. Sure, if I ever finish it I'll be able to say "I was the first guy to make multiclassing work in this particular way!" (Assuming someone doesn't beat me to it.) But I'm writing it mostly because 3.x is still in my head, I guess, and because I love tinkering!
Two different views on the same thing, one sees a problem, the other doesn't. I'm pretty sure that one person trying to fix it would cause a problem for the other.
Sometimes. But other times, I'm convinced that the one who doesn't see a problem would be just as content either way...so long as it was the way he/she grew up with, or the way that the devs wrote it down.