i think many developers forget that us pc gamers have sisters n brothers or husbands or wives or friends that also want to play videogames with us. ya'll already have gamepad support so the addition of a co op mode would be a matter of a couple of easy non resource wasting screen splitting programming, and it would get brownie points from everyone for being the first fps to officially have local co op on pc (which i think every pc fps should have). its simple, one person uses the gamepad n the other person uses mouse n keyboard.
local co op in my opinion is actually underused in videogames, but in addition to whats listed above, it gives a more fun experience cuz its not just the lonely player by himself. i know we have vent n steam n all that, but i would have to buy 2 computers if i want to play with my lil bro instead of a friend who lives 10 minutes away from my house.
besides, i know this is late,
even if crytek patches in a local co op later it still would be revolutionary, and it would give pc players more of a reason to buy crysis 2. even if crysis 2 only had xbox controller support, i would replace my logitech gamepad with an xbox controller JUST for local co op, infact, that would give people more reasons to actually use an xbox controller in crysis 2.