The avatar thing is a bit of a storm-in-a-tea-cup. At the end of the day the way avatars are displayed is a site operators call, in this case @stevebaer gets to choose.
It is super trivial to move back to square for example: http://discourse.mcneel.com/?preview-style=e301120a-6688-431c-9196-349b68c9cc67 … to enable this back here all that needs to be done is for an admin (aka Steve) to click the “enable” button.
Personally, I think round avatars are a good default for new sites because it looks much better on the topic list.
@jeff_hammond will reply to that here User avatar highlighted only if topic starter was last to write in topic