Depends on what you are motivated by. I phone in workouts all the time on my own. But if I am with people that I am working out with generally dont. So yeah, some of what I am paying for is accountablity. I need some sort of group activity to keep me motivated and accountable, and I have longer term goals than just putting in 20 miles a week of running and I think crossfit can help me get there.
I am sure some people have success with it at home, but I have a small apartment, I know nothing about lifting, or weights, or putting a program together, never mind multiple programs. I just put miles on my feet, and I know I need to be doing more than that. Yeah then that is a product for me. Just like different eating programs work for different people.
And additionally, I am in a new town, I know two people, I am having a hard time finding a hockey team that doesnt play at some crazy hour. The people at crossfit were friendly and not friggen meat heads, it will be nice to get out of the apartment and interact with humans that I don't work with.
EDIT: I should also note that I have two friends that have been doing crossfit in Natick for about 6 months now. They enjoy it, they don't have some specific training goals, but they like to just improve at whatever they do. They are C level hockey players, not superstars, play adult league soccer. They just want to be fit, enjoy life, sports and their dogs.