Yes, but atleast they are grouped...
Avatars, all though, put too many images on the board. Some people might disagree with a avatar, and many people use the 50x50 pixel animations.
Sure, some people might disagree with someone else's signature, but it doesn't bother you as much as an avatar. I don't know what I'm trying to say... o.0
You can know who a member is instantly by what else? They're name. I believe that's quicker than definining who's avatar it is out of a possible 100. o.0