There is nothing wrong with reading only light or heavy literature. None should read books just because some people say you aught to do like because it's a "classic" or it's number one on the NYT bestseller list or won the nobel prize.

I love fantasy and science fiction. I read The Wheel of Time and when I was younger I read Terry Brooks and David Eddings. Didn't particularly like Tolkien, but I acknowledge the great impact his literature has had on the fantasy genre.

I also read alot of Haruki Murakami's books. That is literature some would think of pretentious. But to me it speaks to my soul.

I also think people should read more nonfiction. University literature on history, social science and political ideology will have a great impact on your understanding of the world and of the literature you read whatever the genre it is. I'm a great fan of political philosophy by the likes of Foucault and Baudrillard

But then again, when I tire of that I read Conan the Barbarian for instance, to cool my head down. And after that it's good to take on something more heavy again, if feeling for it. I think Solaris by Stanislaw Lem is the greatest Sci-fi novel I've read though some would feel it's boring, uneventful and too philosphical. I think of it as a psychological drama.

Good advise: Read what you feel like reading, try to read a little of this and that, wether it be childrens literature, fantasy or nonfiction. And once in awhile, read a book based on advise, just like you suggested to do.