I think there's a place for them. They're basically a showcase for a lump of hardware, they put the consoles through their paces. A company can sit down and put every second and person onto getting the best they can out of 1 lump (instead of 3 or 4). It's much more efficient, much easier and in general has led to many of the most noteworthy games of the last decade
I guess that means we'll always have the fanboys
but tis a small price to pay for everyone to be catered to surely? I don't want to buy 3 consoles, or even 2 really. I tend to pick the console with the games I want and my PC, and that's more than enough. Last gen it was the PS2, this gen it was the 360, though there is a Wii in my house (who doesn't have 1?!). I'd like to see the lot of them work together more for the good of gaming but what are the chances of that !
Back on subject, it's the same reason we have supercars. They push the limits, there's companies out there inventing new bits to fill gaps and getting the max out of what we do have, to push forwards. That tech ends up all over. If Ferrari had to build a cross-country, family-sized and farm-worthy version of every car, it'll really stifle them, limit them, waste time. Same concept with cosole exclusives.
360 games should be on PC too though, MS you bastards!