What is keeping the PC gaming community afloat is MMORPGs, which derive their revenue from a subscription model (and the occasional expansion). Subcription based PC games want you to pick one game and devote your gaming time to it -- thereby keeping you as a revenue stream (see: WoW, EQ, Eve, etc.)
Console games have a different model - the console manufacturer gets a cut of each game sold, so they would like a game to be really popular, sell a ton of units, and then they want gamers to give up on it and move on to the next big game so that the console vendor gets to tap each individual again. Sure, some console vendors have subscription fees for online use (Xbox live gold) but the revenue from this must pale in comparison to the revenue from someone buying a new game each month.
There is NO reason you could not do a port of EQ or WoW to a PS3 or an XBOX360.... the UI differences are easy -- just plug in a wireless usb keyboard and mouse (a keyboard with integrated touchpad would work fine from your lap on the couch, who said you had to use a joystick?). You could package the keyboard and sell it with the game.
The problem with MMORPGs is that they are sticky -- they encourage gamers to devote their playing time to them to the detriment of other games. This breaks a model where the console is sold below cost and the profit comes from game sales - if MMORPGs for consoles were that sticky, people would only buy and play only one or two games.