I completely agree that one way or another, the car needs to be stopped.
But it is not *crazy* to be thinking about the car behind you either. Newer cars with high-tech braking systems have much better braking ability then the average 10-year-old Honda on the road. On a few occasions, I've had to make a quick stop and then, after realizing I was definitely *not* going to hit the car in front of me, let up a bit to try and give the guy behind me as much room as possible.
Whether he's tailgating me or not, his fault or not, he's a dumbass, whatever... all things being equal, I'd rather not get rear-ended.
So I think it would be cool if the software for any sort of automatic braking system take that into account and stop you "just enough" to not hit the guy in front of you.