You don't get points for losing to a giant-killer. You just get to be a slain giant. In this case, a slain giant that didn't play Iowa State or Colorado and finished outside of the conference's top 2.
Kansas spoiled a lot of things for a lot of Big XII teams this year, but at the end of the day, they couldn't even get bowl eligible.
It doesn't get much easier than 5-7 (3-6 at the time) Kansas at home...
And for what it's worth, yes, it's worse than losing to OU. For starters, OU is 6-6. But it's also worth noting that they're in the SEC and ran the Big XII for years. 6-6 SEC team > perpetual doormat 5-7 Big XII team.