In a playoff, what you are doing is crowning a champion of that playoff "tournament". You are not saying that the winner of that is necessarily the "best" team overall, only that they did what it takes to WIN THE PLAYOFF. That criteria is objective and fixed. There's no "eye test", it doesn't matter how bad you beat teams in the games, whether or not you have key injuries, or anything else that's subjective. That's the beauty of such a system.
However, when you take that and corrupt it by having some SMALL committee of humans just decide who "deserves" to even have a chance to participate, when the criteria are unclear, not communicated, evaluated in secret, and seemingly change year to year, you've moved us into a system that, in my opinion, is worse than ANY of the prior systems. I'd take the BCS, or even the pre-BCS bowl system and national championships that were KNOWN to be opinion-based, over this bastardized disaster we've got now.
Don't worry about a system that sometimes lets teams in that "don't deserve it", because "deserving it" is a garbage criteria for determining a champion.