Again, from a psychological perspective, we human are exceedingly poor at remembering names. How often have you been introduced to someone only to not register or immediately forget his or her name? That is normal because we tend to focus on aspects other than the name to remember identity - hairstyle, body posture, attractiveness, etc, with the common denominator that most of what we remember are physiological, physiognomesical or attributal aspects.
Kagus remembers my name because we've called each other names in a heated debate and he thought I was an Avatar of what's bad with the 'net (hope you're dispelled of that notion now, btw!), Capritastic I remember because we usually post in the same threads and are both quick to poin out duplicates, and draco I will remember because we've been on the same side here. However, it is also noteworthy that me and Kagus have been on the same side of heated and quite deep debates in the suggestion fora some time ago and he didn't remember me from that, or he wouldn't have thought me to be a 1337-sp33king haxx0r bringing disorder to this community.
Then there are hundreds others users here. I'm sorry, all of you other, but you're in the teeming masses. Your nicks don't mean anything to me. We may have bantered exchanges in threads for a long time or it might be the first time you've posted - I simply wouldn't know. Now, if you had a distinguishable avatar, you're likely to be remembered. If you also have a signature that help me fire associative synapses, then you're even more likely to be remembered by me, and your prior statements taken into consideration.
When writing normal, physical letters (yes, some of us still do - it is NICE to get a letter!) we start by saying something like "Hi, this is James", and we end them in a signature. This is a very imperfect analogy with forum posts, but the point that avatar and signatures establish and enforce identity is undeniable. I personally prefer communication with people I recognise, whether I like them or not, and dislike anonymous conversations over time. Also, "anonymity" (in the sense of lacking recognisable identity) tend to be more passionate, inflammatory, generalising and insulting, than when you have an identity to nurture over time.
So, the overarching points are, (1) established identities are better for the development of communities; and (2) if we want to be remembered or recognised, then we want to provide as many queues to trigger associations as possible. If you want to be hated and shunned, then make your identity attributes as obnoxious as possible, but this describes exactly how many of us?