I just read a 3-1/2 year old thread that explained why the avatars were no longer centered--and it said it would be fixed eventually. Can someone tell me when that might actually happen? I find the current half-cut-off, can't-tell-what-they-are look kind of annoying!
Okey-dokey then! 
I'll take the lack of response as a "no, they won't be fixed any time in the foreseeable future."
@Remedios wrote:You are free to upload your own image and use it as an avatar.
There are no centering issues that way.
No, actually, I wasn't able to upload my own image. 
There was no option for that. Otherwise, I wouldn't have asked! 
NOW I can. And I can adjust its position/cropping, too. Once my status changed to 'regular contributor' the option to upload my own avatar FINALLY appeared. Yay!
That's why I came back here just now, to update the thread and let others know: you're eventually going to get the option to use your own [nicely centered] avatar, but you have to reach a certain level of participation first.
Case closed. Mods please feel free to lock--although for those stuck with uncentered avatars and *NO* option to upload their own, this doesn't help.