Many of them use mechanical keyswitches, which have numerous advantages over the plastic or rubber dome switches used in cheap keyboards. You don't have to bottom out the keys, which is much less painful for your fingers, hands, and wrists, and they provide auditory and tactile feedback. The keystrokes are also smooth and predictable, not mushy like on a cheap keyboard. Mechanical keys are also much more durable. A good mechanical keyboard will last for decades. High end keyboards also tend to have N-key rollover, which allows you to press many keys at once, and they all register. This is very important in fast paced games that require rapid keystrokes. Your crazy Korean Starcraft players will take advantage of this in a big way, rapidly issuing commands to their units. It can also be quite helpful in FPSs.
The PS3 supports it, but the devs don't really. Unreal Tournament 3 was one that had keyboard and mouse support. You could also get this, if you desperately require KB/M in all your games. http://www.amazon.co.uk/PS3-Eagle-Mouse-Keyboard-Converter/dp/B0040UAYI4 I googled N key rollover. I now know more than I ever cared to know about keyboards.
I imagine using a kb+m combo on consoles will be bad like using controllers on PC. Console games are optimised for controllers right?
ever played THPS on a keyboard?? Some games are just made for controllers and visa versa. And on the topic of RSI would a touchscreen reduce the effects? No good games that use them but might it be a thought for the future? Kinect?