I don't see how it would be possible to play the first Witcher with a controller, though I guess the second one played fine more or less with one. PC version of TW3 though is going to have an entirely different UI this time, that works better with kb+m compared to TW2's UI.
Not to mention I'm pretty sure the PC focus of Dragon Age after the first game was pretty much dropped and that'll probably carry over to this new one.