Well, I think that saying that any controller setup is always equally good is not very acurate... Most FPS games are usually better played with mouse+keyboard setup, and one of the evidence for this is that lots of console FPS games have lock-on features...
As for the analog stick vs the WASD, well, 256 levels in such a small "travel" is REALLY sensitive. 90% of the games employ just 4 to 12 levels, probably. It is quite easy and simple to simulate that like they did in Splinter Cell on the PC, where you can set Fischer's speed with the mouse well. We all just toggle between tip-toe and mad-dashes directly, anyway.
Even though it is more than POSSIBLE to play WC games on gamepad, keyboard and/or mouse, by my own experience I can say that the most intuitive and adequate interface device is the joystick, considering how they designed the game to be that way. I've played Wc1, 2, Priv and Academy for a long time with just the keyboard, and when I switched to joystick I just played a lot better, as I guess was the case with a lot of people....
And Chris, aren't those controllers to be used with just the game that came bundled (and a few others, released specially to work with them)?
I also played FPS games with just the keyboard for a long time, and I simply sucked, I even tried playing Dark Forces 1 with t joystick, but it was crappy too... Then I learnt about wasd+mouse, and I made progress by leaps and bounds...
I guess most kinds of games are playable with most kinds of controllers. But in most cases there are some controllers that are better than others.