I figured it had to do with AI, but I thought it might also have to do with the community.
Here's the deal on AI. It won't be possible to make bots anywhere near as skilled as good players for a couple reasons. First of all, real players have a high framerate enabling them to do crazy jumps and whatnot. The server (what all the bots would run off of) runs at basically 10 fps. If you've ever tried playing at 10fps, you'll realize how difficult some movement is.
The second thing is, of course, making the bots "intelligent." A lot of gameplay is about improvisation, which is practically impossible to code. Getting anything remotely intelligent will require a lot of time -- time which could be dedicated to other elements of the game.
That being said, should I still work on bots?