Also you can sit back from your desk no problem with your keyboard and mouse, there are things called slide out trays, they're actually quite convenient. There are also things that mount directly to your chair, in the event you're not already executing a superior couch / bed set up.
It's not about the distance I play at away from my TV. A gamepad is more ergonomically comfortable over kbam. It's much less strenuous on the hands to play with a gamepad. There's a reason many disabled gamers on the Steam forums complain about a game not supporting gamepads. There are many reasons that someone might not be able to play with kbam while they can do so very easily with a gamepad.
Also your assessment of Borderlands 2 is far from correct and obviously clouded by your own extreme bias. Try looking at things more objectively. Killing Floor is a co-op shooter and, whether your like it or not, can be played casually especially on the lower difficulties. The main draw of the game isn't that it's "skill-based" for everyone, though that seems to be the case for you. You can play on the higher difficulties and that won't at all be affected by supporting gamepads. If I decide to play with a gamepad it's because I want a more casual experience with friends and family and that's when I play on lower difficulties. KF is very much both a casual-friendly and extremely hardcore, difficult FPS without sacrificing either gameplay style.
You're also underestimating how well some people may play with a gamepad. Sure, it's nowhere near the skill one can achieve with kbam, but it's not quite as bad as you may think. I've seen some very impressive gamepad players out there even when they disable aim-assist. The point, however, is that Tripwire needs to appeal to as large an audience as they can and they certainly seem to be doing very well so far without sacrificing the integrity of the game. Gamepad support only helps increase the appeal of the game and if you feel that it's a detriment to KF2, then you are sorely mistaken.
Try asking yourself this: "How will gamepad support affect my enjoyment of the game whatsoever"?
You'll probably say something like:
- Gamepad players will join my game and play much worse and ruin my experience!
-- Well, wouldn't any bad player regardless of their preferred method of input do the same for you? If they bother you that much, then kick them.
- The game might be balanced for gamepad players and the game will be too easy!
-- Considering how TWI's stance seems to be balancing for PC players, it's very safe to say that it will be balanced for kbam because it is still the most preferred method of input among all PC gamers when it comes to FPSs.