I get yelled at for saying this but children enjoy a challenge and it's good for them to read books that are a bit difficult. In my experience, adults are the ones trying to keep them from classics while the kids are aching to read Homer, Jane Austen and Jane Eyre.
Just sold a copy of the Iliad to a 10 year old who wants to try Homer. She's read 5 Percy Jackson books and wants "the originals" now. Kudos to her and to her mom who brought her down to the bookshop.