Avatars are likely to be popular with people who see AB as a 'community', where discussion can take place (either 'seriously', in topics like News, or 'informally' in Chatterbank).
Those who simply
ask questions in 'Technology' are often only interested in getting a factual answer to their question, so they don't feel part of the 'community'. So they see no need to 'personalise' their posts with an avatar.
However plenty of the people who answer such questions also use other sections within AB, so they do choose to have avatars.
Here's an avatar for Pusskin:
http://www.notimeforflashcards.com/wp-content/uploads/2010/02/Mr-Pusskins.jpg