I don't think reading is good or bad in itself. I enjoy reading, while other people prefer going to the movie, listening to music, hanging out with buddies, or collecting "friends" on Facebook. Does that make me a better person than they are? I doubt it. I certainly have access to things they are missing on, but I'm also missing on things they enjoy (well, except for the Facebook thing, I'll just pass, thank you very much).
As for the content... well, any kind of message or data can be hurtful if you don't take it in context. Reading My Kampf as a way to learn more about Hitler and how he came to power may be good. Reading My Kampf in order to use Hitler as a role model is bad. Reading My Kampf while not knowing what Hitler did once he was in power can be dangerous.
Encouraging people to read is great, but teaching them to assess what they are reading and place it in the context it was written in, and teaching them to make up their own opinion instead of just absorbing what they read, is even better.
So yes, maybe reading can be bad in some circumstances, but ultimately it's up to the reader to figure it out. What we need is better educated readers, who can read potentially dangerous books, not a committee to identify dangerous books and ban them or label them.
And let's not forget that most of the reading nowadays is not done on books. It's done on the Internet. Which makes the question of educating readers even more relevant and critical, I think.
Funny, I had no idea when I started typing my reply that I was going to say something like this