One of the principles that the recent BCS hearings were built on was that the BCS is inherently restrictive in who it allows to play for the national title. Specifically, it doesn't let anyone from the non-automatic qualifying conferences in.
The idea is that human pollsters will not give the non-AQ conference teams a chance. Well, some people think those non-AQ conference teams are not alone. They say that some of their AQ conference bretheren have been kept out as well due to lazy voting.
To get an idea as to how restrictive the college football system is, I went back and looked at who got to play for a championship in the four major pro sports plus college football and men's college basketball. I counted up the number of unique teams that got to play in each sport's championship round.
The span I chose was from 1992 to the present, since '92 was the first year college football attempted to have a "national title game." Of course, the Big Ten and Pac 10 didn't participate until the BCS, so for 1992-97, so I used the top two teams in the AP Poll. Presumably, the AP No. 1 and No. 2 (or approximately them) would have played had the two laggard conferences joined in from the start.
Here's what I found. Remember that MLB and the NHL have two fewer possible teams than the others since they had a strike and lockout, respectively (?), cancel a postseason:
The NFL is built with parity in mind of course, so it's not surprising to see it have the highest percentage of unique teams (22 of a possible 34). It's somewhat a surprise to see college basketball on the relatively low side, given that the tournament has a reputation for being a random crapshoot. As it turns out, there's a relatively familiar feel at the end.
College football though isn't just last, it's dead last. The dynastic NBA, which has had just eight (!) unique championship teams since 1980, managed to get three more unique teams in the finals than Div. I-A football has.
College sports are a different beast than most pro sports are, given that no salary cap exists. Excellent recruiters can go out and sign as many studs they can each year. However baseball doesn't have a salary cap and the NHL didn't have one for much of this time period either. Plus, scholarship restrictions were supposed to level the playing field to a degree.
The most likely explanation for the lack of diversity at the top of college football is the fact that the top is determined by opinion polls. When voters are uncertain, they put the same comfortable set of teams at the top: USC, Oklahoma, Florida, and LSU nowadays; Nebraska, FSU, and Miami in years past. It's human nature.
Imagine a hypothetical seeded plus one going back to 1992, using the last regular season AP Poll from 1992-97 and the final BCS standings from 1998 on. Such a construct would give 11 additional unique teams the chance to play for it all. Even if only a quarter of those No. 3 and No. 4 teams won their hypothetical first game, it would up college football's unique team count from 15 to the 18 that the NBA is at.
Boiling things down to just the BCS era gives this:
College football doesn't even average a single unique team a year in the BCS era. If it feels like the same old teams playing for it all every season, it's because they basically are.
Even just a simple seeded plus one would have allowed two additional SEC schools - Georgia (in '02 and '07) and Auburn (in '04) - a chance to take home some hardware. Going back to '92, it would have allowed some of the historical have-nots (Northwestern in '95, Kansas State in '98, Oregon in '01) a chance to get a ring. Not that anyone was beating '95 Nebraska or anything.
The point is, everyone who says the BCS is exclusionary is right. It's not just the BCS though, since it goes back ever farther. Over at least the past 17 years, no other major sport has been as exclusionary as college football and it's not that close.
Only two teams have been so dominant in that span as to have won every game by at least two touchdowns: '95 Nebraska and '04 Utah. That NU team showed itself to be one of the all-time greats; that Utah team didn't have the chance to with its schedule and bowl opponent.
Regardless, every other undefeated team has shown itself not to be untouchable, and sometimes the better team loses a game. There's no way to know for sure if any past championships would have gone in different hands under a plus one (or any kind of larger playoff system), but at least more teams would have had a shot.