Try looking at one of the threads in this post, I'm struck by how much easier it is to follow a discussion at a glance. You see pink avatar talking to green, pink, green, oh here comes orange. You immediately know someone new jumped in with new info.

Also yours kinda looks like a portrait of a middle aged 8bit character.

Edit: Gotta admit though, on the front page it looks kinda goofy.

For me the use case is: someone leaves a comment that's ambiguous, someone asks for clarification, some people respond _what they think that original commenter meant_, finally originally commenter solves the doubt.

I find myself Control+F the name of the original commenter to see if he/she has replied, because I'm interested in _that_ response — not so much of the interpretation of others.

> The content of the comment is much more important to me than whoever posted it

I agree with this sentiment. I mostly did this for fun, however I will point out that occasionally people get mixed up about who they are responding to with regard to which comments in a thread came from which author, and a random avatar can help to prevent those mistakes.