Do you guys really think that an avatar detracts from content? REALLY? That's like saying fancy rims make a driver a worse driver.
Yes it's vanity, but why do you care about what image I use for my avatar? Create a custom style sheet for the site and add a display: none attribute to that style for avatars. Problem solved.
The Wordpress suppport forums are a GREAT resource and have avatars. I have never once said, "wow, this thread really loses credibility because the OP has a Soprano's avatar."
I don't know any of you or remember any of your posts. Given some time and an avatar to tie to your nickname? I am more likely to feel like I know you and feel like this place is a bit more social. You make a place feel like home and you will increase the community activity IMO.
On twitter, where we almost all have some sort of avatar uploaded... and for those that I'm following for WW, I now can recognize your avatar "signature" if we had one here. Simply extending the social community even further.