I dont mind the unlock system at the moment as I'm working my way through the career. The rate of progression is fast enough to not be too much of a hindrance and make it feel like you are "developing" a car over a season. However, I can see this becoming a big problem when I'm finished or had enough of the career mode. especially as cars are released through the car pass. Maybe I just want to jump in the new car, mod it and take it for a spin... Its effectively forcing you to complete a full race series, maybe even more than one if you really want to unlock every upgrade feature, something I'm not prepared to do, and I have no intention of playing this online. I see Forza as something I will pick up when I've not got the patience or energy for full on sim racing, but still fancy playing something motorsport related. If its going to become a chore it will end up being uninstalled.
As for crashes, I've had one whilst loading into track, though I'm not entirely sure Forza was completely to blame. Moza software also crashed at the same time. so I wonder if there was some sort of conflict that caused it.