"Hi! I'm Taylor Swift! Listen to me sing this song about how I'm a teenage girl who pines for guys who just aren't that into me!"
If you're not a teenage girl and you like Taylor Swift, there is something f**king wrong with you.
Also, if a song is good and in Guitar Hero, and not part of some exclusivity deal, you can guarantee it showing up in Rock Band as DLC at some point. So you buy your terrible Band Hero game, and play all the Pink you want, and I'll just spend two dollars on American Pie when it comes out as DLC for RB.