Avatars: all important or just a nice extra for the profile?

How important is an avatar (profile picture) on Fluther? Does it play a key role in identifying users, or is it just a nice splash of color on the pale blue and white page?

Does the quality/contents of an avatar matter? If so, what makes a good avatar in your opinion? What makes a bad avatar?

(I have a feeling this may have been asked before. However, I ran a search and went all the way to the tenth page of results with zero matches. So, don’t waste your time by posting a “use the search function.”)