John August nails my thoughts on MySpace (and probably yours too):

The difference is, I like Google, and I kind of despise MySpace. Yet the reasons why I dislike it are largely why it’s been so successful.

Visit any random profile on MySpace, and you’re instantly beamed back to the Bad Old Days of web design, with flashing graphics, unreadable text and — worse — random songs that start playing unbidden. It’s not that the underlying template is ugly. It’s blah but inoffensive. The ugliness comes from how easily an individual user can modify it, cramming it with non-scrolling backgrounds and multiple video streams.

(The fact that MySpace can handle the load is testament to some serious hardware and deep pockets.)

Because most people have terrible design sense, most profiles look pretty terrible — but they look exactly how the user wants them to look. This element of self-expression is a large part of why teens and tweens and twentysomethings love their MySpace.