I agree, and it could potentially be a fun bike given the technology available to BMW. I think that they could leverage some of their engine development expertise in the K1300, SS1000, and 1600 engines to come up with something bulletproof, with a 4 valve head and EFI, 27-30HP and decent tractability should be possible. They key will be to keep it price competitive and light, and simple enough for new owners to adopt basic maintenance of without having to go back to the shop for a $150 oil change every 3000 miles.
Somedays I also wish for a simple single, like the GB500 Honda or the ol 1979 Yamaha SR500 I lusted after as a teenager. Yamaha has come back with an SR400 now that tends to pluck at my heart strings every now and then, but I think I'd have to give up one of my 3 bikes in the garage, and I cannot think of which I could possible trade away-perish the thought!