Probably OP never been in forums where animated avatars are much larger and there is really huge animated signatures too. Many are like competing who got the most flashy and shocking one.
Oh yes I've been in the 90's too you know 
I'm tempted to use a rapidly flashing avatar just to demonstrate how bad they are...
The risk is that you'll chase away all the serious users and all the lolcat fans will stay to admire your flashing avatar. And then they'll decide to forbid NON-animated avatars I'll take the more libertarian stance and instead of trying to have it enforced I'l simply not help or respond to people with an annoying avatar.