Hmm, i think many who come here are scared away by the design or the simplicity (1997 forum style) layout.

No images beyond the main 'click enter page' feels like a website run by a 12y old who cant do html (but is awesome @ scripting lol)
All basic forums have smilies, and can post images, resize text etc.. Everyone here (almost) is posting as anonymous and there is no registering, the "create new thread" is at the bottom of the screen so you have to scroll it and same goes for the reply form.
These things probably scare people who are used to myspace,xanga and gaialike forums with eyecandy, flash, images and cool layouts. It's like an alien world.

And yes, 4-ch can beat 2ch in size, there no doubt about that because 4-ch uses english as the main language and well, yeah..