Interesting enough, 95% of this thread is people (more than likely)too afraid to post pictures commenting on 5% who are comfortable enough to do so.
But, if I remember correctly from browsing through the older pages a couple months ago, people were posting pretty frequently years ago...I wonder what happened.
The site was a much smaller community when the thread started and it blew up instantly because everyone was like, this is finally our chance to show other people what we look like (not a common thing at the time) and some people were posting dozens of pics and it was kind of a, in-the-moment thing where even the people who normally wouldn't post pictures of themselves did (even if they deleted them soon after). The thread was growing ridiculous fast (especially by the standards of the time) in those first couple hours. You have to think of it, as this thread was the first time people on the site were presented with the notion of sharing their pictures with the community and they took advantage of it because it seemed new at the time.
Now, a lot of new people use pictures of themselves on their profiles or in a more casual manner because the Internet (and ComicVine) is pretty mainstream so people don't worry about disguising themselves and everyone else has already posted pictures of themselves in here. There's no longer this stigma of posting a picture of yourself on the Internet so the people who would do it wouldn't see the need of a thread dedicated to it.
Currently, the only people that need to post in this thread are new people who think of sharing your picture as an ice breaker and people who've been around a while, shared their picture once and now just think of it as a fun thing every now and then.