Yup, well I've noticed that all the avatars/signatures on here have rounded edges, and the avatars all have the semi-circle blended into the background. Is this a requirement? I know it sounds pretty dumb, but I'm confused.
Nope, not a requirement at all. Just a lot of people like the look and style I guess, so it's kind of a "fad" maybe. You're welcome to make your own avatar any way you like, or you could request one in the graphics section.