The BCS formula got the two best teams matched up to play in the NCG. I don't know what more evidence is needed to validate that the system is a great success, given it's stated goal of pitting the nations top 2 teams against each other in the NC.
The BCS allows college football to have a regular season that is unrivaled in excitement and meaning in all of sports. I won't go so far as to say that "every game matters" but without a doubt, more games matter in CFB's regular season than in any sport. Consider the alternative of the NFL where you watch 3 months of glorified scrimmages, a handful of meaningful games in December and 4 weeks of playoffs. At the end of the day, NFL teams aren't rewarded for being good from September to January, all that matters is getting hot at the right time. In college football, it's very tough to win a championship and take a week off, and certainly taking 2 weeks off knocks you out of contention for good.