Lack of time to practice is the biggie for me. I'm, by and large, ok with my phrasing, and I've been playing long enough to get to the point where the technique limits I have I look at as part of my style as much as anything else.
But, the whole graduating from college and getting a real job is what's doing me in. When I have time to get in a couple hours of practice a night, I'm generally pretty happy with my playing, but these days that's rarely a sure thing, so more often than not when I pick up the guitar to record, my technique is rusty so I'm fighting to do things that should be easier for me, and my calluses are shot after only a few takes. It sucks. :/
Aside from that, my picking hand has always been my weak link.