I've never played a FPS on a PC but do play RPGs like DA:O Skyrim, & Oblivion and RTS on the PC so I'm familiar with PC gaming . However is it really that difficult to line up a headshot with a mouse? I don't mean to sound demeaning at all but is it as challenging as using a controller to aim?
EDIT:
Not entirely. You put a modifier on it. If Headshots did x2 (or whatever number you want to associate with it) that would work. Attacks made to legs slow your target, attacks to arms slow attack speed etc. I think a stronger sense of locational damage would be great, however considering how fast paced the game is this really benefits bows the most, which as it stands are already bordering being overpowered with the damage they deal.
I think they've done that in the fallout series, I don't see why they couldn't do it in skyrim