Well it's a kids' game. But it's a real question. Iowa State unquestionably played a tougher schedule than Cincinnati. They also lost 2 games. Where is the line? 3 games? 4 games? 5 games? They beat Baylor and Texas by a combined 10 points. If they lose those games, why shouldn't they still be ranked ahead of Cincinnati?
The votes dictate where the line is. Obviously, if Iowa State lost to either Baylor or Texas (very unequal losses, btw), they'd be ranked lower and probably lower than Cincinnati.
I've talked about this at length previously. There is a real, factual chasm between P5 and G5. You asked why even rank G5 teams at all,
and you're right - to not rank them would be more honest. But to provide the illusion of equality, G5 teams are ranked in the top 15 around the middle of the season if they're undefeated. And if they're up there, they get a crumb from the big kids' table in their bowl game. And then they go away.
It would be more fair and honest to tell G5 programs that they're in limbo and don't have a realistic shot at the national championship. Because they're not FCS and not P5, they literally cannot win any national championship (unless they invent their own, like UCF did).
They are in purgatory. It sucks. It's dishonest to pretend they have a shot, because they very much do not.
But bringing it up year after year is boring. It is what it is. There are other schools with much more to gripe about than Cincinnati. Do what Utah did, and until you do, deal with the reality.