Its not just ugly as some kind of aesthetic issue, it also hurt functionality. Buttons could be moved or made invisible. Animated backgrounds would make things hard to find, etc.

But that's not MySpace's biggest sin. Its biggest problem was all the freedom it gave just helped turn into a defacto dating site. With no real rules and no focus on anything, girls put up lots of cleavage photos for attention and guys hit on them. Guys put up shirtless leering photos and girls responded. Comments were more often bawdy talk than not. Teens and 20 somethings ruled. It never migrated past a high school mentality. A bit like how Second Life has now pretty much become a fetish site for furries.

Then Facebook showed up with its academic focus. The existing userbase were all college students whose peers, professors, potential employers, family, etc had access to their profiles, so there was a disincentive to treat it like "da club." People put their personal and semi-professional faces up and when the floodgates were open to Joe User, he saw the culture there, the lack of customizations, etc and conformed to what Facebook was. It had the mainstream professional and familial mores its roots were built upon. The Wild West of the Myspace world was just too self-limiting in this case. It couldn't go mainstream with its culture. It was too "young person trying to get laid" focused.