Like your idea it reminds me of the Playstion contol buttons there pressure sensitive, Comes in handy when playing GT4.
I do think BMW could somehow come up with a pressure sensitive paddle. You could still have the mode/program and select it as a default setting. Like being in S2 then wanting to shift really fast to pass a car S5, then the system would revert back to S2 for better gas milege.
I've driven in S5 (99.9%) since I bought the car if I need more power just a double flip (or one) of the paddle and insta power. The other modes are to jerky and slow I really wanted the feeling of fast shifts when I got the car, even just driving around town (bumper to bumper is another story) but that's just my opinion. Wonder what everyone else thinks.....