I don't think guilty is the word, but I often think "man, I don't have the time to play all the new game" while at the same time replaying the same game again (atm I'm playing trough zone of the enders 2 and xenosaga 1, both game I've played trough at least 4 time each).
But replaying game is great because even if the game doesn't change, we do. And so some stuff I didn't like as a kid I found quite liking and vice versa (I have no idea why I was so tolerant of grinding as a kid, prob cause I only got a new game every 2-3 months). Plus some game have great replay value trough gameplay or story (FFX story is better the 2nd time around imo).