Because it would take me at least 15 mins to drive there.
Seriously though, I've already done the "put a face with the name" thing with most of the few people that I deal with regularly and even that isn't necessary.
Plus, a shiny booth with shiny booth babes or free drinks/parties isn't gonna make me rethink where I send my traffic so there's not much point.
I get more value out of the 0.1% of posts on GFY that contain useful info than I do going to shows generally.