Its funny how you mention gamers with half a brain, when you don't even realize that Valve does not use FP16 for HDR. They are not using true floating point precision HDR. They are using a fake SM2 "bloom" effect.
FP16 HDR + AA cannot be done without major workaround. PERIOD. It doesn't work on Oblivion, it doesn't work on Lockdown, it doesn't work on Splinter Cell, it doesn't work on FarCry, it doesn't work on Timeshift, it doesn't work on Serious Sam 2, and it doesn't work with BoS.
It can be done with x1900xtx cards, but requires a major workaround, and is simply not worth it for 1% of the population. Frankly, I would rather have them put that dev time towards something else.
I would like to see the option to disable HDR though, but they may have done it for MP balancing issues.