I think 'money talks' is the obvious and true reason for a conference championship game (who's gonna turn down money?), but the concept also has merit. Look at the Big10+1 where every year you have about 3 teams that might play for their crown, and there's always the question of 'which team in their conference did they NOT play?'
Axl pointed this out.
Pac-10 does have 10 teams, so I can't knock that, and I would assume that they play ALL their conferencemates every year? Or do they have to rotate the schedule and always leave someone off? I ask as someone who honestly doesn't follow the Pac-10. Smaller conference, yeah, you get an honest regular season champion, and I can't argue with that a bit. It's just not the norm after the Big12 and SEC did it and the ACC followed suit. I wouldn't be surprised to see the BigEasy follow suit before long, especially as they need more money to improve the league - something neither the PAC10 or Big10+1 have to face.