I find this to be ridiculously insulting. I've never met a person who said that guitar hero and rock band changed what music they liked. I'm 20 and have only ever listened to classic rock. Real classic rock, Zeppelin, The Who, The Guess Who, The Boss, not Nirvana. It has nothing to do with Itunes or video games....
Oh? Well, I find your post to be ridiculously under thought.
(A) of course! Silly me! Every teenager grew up just like you with all of the brains, good looks, charm, and most importantly independence in the world with that classic "I don't give a !@#$" attitude. Man... I'm sorry dude.
(B) Your 20! Woo! And... I'm 21. Now, if my stupid little brain can comprehend simple math, I'm... let's see... carry the 12, under the 4, jump over the hole, around the loop, and into the... ONE year older than you! Wait... when these games came out, I was past my IMPRESSIONABLE years. Hell, I was in college! Yet me and my friends did have fun picking up a few favorite bands from the game and guess what! Me and my brother (ca. 1996) picked up bass and drums because of the game! (I'm not going to mention that all of the songs he learned first were from the game, or that he and all of his friends asked for iPods that Christmas, or that they all downloaded EVERY song from the game to play on them... nope, that's "ridiculously insulting"). Now, it seems to me that everyone at my college and around my age in general still liked Brittney, NIN, Backstreet Boys, Nirvana, RHCP, RATM, etc. But everyone at my brother and sister's soccer games, parties, etc. were listening to The Who, Pearl Jam, AC/DC, etc. ... bands from those games.
(C) Most kids have dropped those bands now (but many of those you actually play an instrument didn't because they recognize the creativity and level of dedication to music bands possessed then). Why? Because it was a fad. Listening to your dad's music was cool. What do they listen to now? Ke$ha, Lady Gaga, Bieber, PSY (*sigh* makes me sad), etc. because they are the "in" thing ATM. If you don't believe me, go look at the vids on YouTube. These vids are getting 10 times as much as some "Classic Rock" songs are in their lifetime on YouTube!
(D) Of course, people are totally going to go around saying, "Hey [INSERT YOUR NAME HERE]! I totally get my musical tastes from video games! I love video games and like the sense of accomplishment I get from playing a fake instrument to songs my dad grew up on!" just like you would tell your significant other the chick behind her is smokin'!!!
Now, since you've accused me of insulting your age bracket, realize I'M IN THE SAME ONE and that you aren't a teen right now... who knew?!