I think, more important is that the way fglrx works now doesn't allow independent developers to make something like bumblebee, because fglrx works directly with intel driver by means of dirty hacks (not surprising that why Chris Wilson doesn't want to do anything with intel driver in order to keep compatibility with fglrx).
For example, even if I don't use discrete card, fglrx is still loaded. That's why if something is wrong with it, I can't even use intel driver. (Usually it means segfault of Xserver).
And finally, there is no other choice for >=HD77XXM users since radeonsi isn't mature enough.