A good, and appropriately narrowed discussion, of why the Percy Jackson books may be their own reward:
... one of the messages of Percy Jackson, and of a lot of kids' literature, is that children are not just waiting to pick their lives up when they're grown, but are heroes of their own stories now. That's a lesson that adults have trouble with, if the condescension and contempt in the discussion of children's reading is any indication. Maybe the people who really need to read Percy Jackson are the grown-ups.
Again, I'm of two minds. Yes, it helps not to give kids something too stale for them to chew on, and if they blossom all the more enthusiastically because of something trendy, great.
That said, I'd bet what they find stale and antiquated is something best left to them to discover, and not something dictated to them arbitrarily. And in the long run, it helps to get them to discover the stuff that has stuck around as long as it has for good reason.
So, there does need to be a way to reach the classics, but let's not count on YA fiction as a way to do it. It'll save both the classics and YA fiction from taking on burdens neither of them benefit from.