First off, let me say how awesome this game is. I have been playing guitar for 4 years before I bought this game and I've always had the worst problem learning my scales. With the help of the scale runner game, I can easily play any skill I would like to and it makes it fun to learn for anyone who is looking into playing a guitar. I also like how the actual song set up is, easy to learn every song but it also advances you as you progress in a song. Here is some bands I would like to learn more from:
Coheed & Cambria
Credence Clear Water Revival
Zac Brown Band
Bullet for My Valentime
Goo Goo Dolls
Fall Out Boy
Its not so much copying the songs as guitar hero has as it is copyright fees and regulations. For example, Rocksmith has to pay each artist for these songs and when you are looking for some well known bands, they are going to want more money for their songs. Guitar hero wasn't even able to get Metallica nor AC/DC until way much further down their line because it was costly and over time and their sales they were able to purchase songs from them.
Currently I enjoy their selection of songs that they have now. If you want some hear/passion, then look at their Black Keys selection, just two artists make up their entire band and they know how to bring some old school blues and new age rock and bring them back to the perfect measure.