Sometimes you don't know what you like. I think it is important to teach the classics.
My 7th grader son is not liking the books he has to read in school. I've been trying to get him to read some classics on his own. He finally read Tom Sawyer, and loved it. Now, he has Huckleberry Finn. I've bought a few other classics for him to read: Treasure Island, Robinson Crusoe, and some others. He hasn't started those yet because he is re-reading Harry Potter.
I wish that there were more literature choice at his school: a sci-fi/fantasy class, a classic novel, or a romantic novel class. My daughters would love a sci-fi/fantasy class as much as my son.
Reading is a recreational pastime you're trying to impart on a new audience. You don't make excuses about them not knowing what they like yet, you make it fun for them or they won't do it again without coercion, period.
Would you take someone who had never had foreign cuisine before and start them at a Japanese restaurant with raw octopus?
Or take someone who had never been camping before out in February to shiver in freezing rain eating cold canned beans for a week?
How about take a novice shooter out and start them out with a .458 elephant gun and no ear plugs?
Start a non drinker friend off with straight scotch whiskey?
So why would you ever start a novice reader off with boring classic books? It may be important to read them at some point in life, but youth is not that point.