I would like to see a wider breadth of car driving games, and agree that they are very watered down. I have played the ultra realistic ones like GT3, with a force feedback wheel (it's in the shed gathering dust now) and they are incredibly involving but I just haven't the patience and time to put into them.
I think that, if the latest iteration is anything to go by, NFS agree with you and have started to put some more choice back into the game as far as the mechanics of the driving goes. With the option to turn off the 'rails' it does seem that this is so.
That said, NFS: Underground was the first driving game I bothered with. Gran Turismo didn't light my candle. I loved the drag racing in NFS:U and got into the rest of it through that.
So yeah, I get what you're saying about NFS being a certain way and there being no need to change it as there's a million other generic driving games out there just like the one they changed it to, but I don't agree. It's special to me.