I follow CrossFit Football, which I don't see as mainstream CrossFit at all. It just uses the "CrossFit" name to gain greater exposure, it's nothing like the mainstream site.
Its main aim is to create bigger, stronger & faster athletes by emphasising strength through a linear progression programming. The strength portion of the workouts are the same sets & rep scheme every week. Only difference is the conditioning workouts, which change on a day to day basis.
I follow it because I want to be bigger, stronger & faster. I use to just lift for strength with rarely any conditioning (just on the odd occasion when I could be fucked) until I realized that I was becoming a fat fuck and now after following the programming exclusively for the last 6 weeks, I've dropped a couple of kilo's and gotten myself into some sort of respectable fitness level.
I know I don't have to follow it, could've just thrown in some conditioning, but I enjoy the variety of the workouts and they're pretty tough as well. I also really love NFL, and in my own mind can just pretend I'm training to be the next Clay Matthews.