So, if 68 of 360 get in, that's about 19% in basketball.
8 of 130 is 6% in football..
So, your point about the numbers is not valid.
Is an 8 vs 1 upset in college football less likely than a 16 vs 1. I'd say not, considering how many years it took for that to happen.
Regardless, whether an upset is plausible or not, is not the issue.
It's about inclusion. If there's a playoff, you want all 5 P5 Champs, top G5 team and 2 wild cards.
Sure, it may end up every year 1 vs 2, but how many years do you see all 4 number 1 seeds in the Final four. Things happen.
If all you want is to ensure 1 v 2 every year, do away with the playoff and just have a title game.