Why do the bonus tracks in Harmonix games kick so much ass?

[espher]

All of the ones in Rock Band kick ass. Timmy and the Lords of the Underworld is not alone in the sheer kickassitude. They're pretty much all indie bands. I've been listening to Outside for the last three hours.

There are a couple that really stand out to me.

Tribe - Outside
The Mother Hips - Time We Had
Freezepop - Brainpower

Oh, and of course...

Timmy & The Lords of the Underworld - Timmy & The Lords of the Underworld