23 years old...
Of course, there was a few really good so called Classics that I read when I was growing up. My favorite book when I was 7 was Charlotte's Web (best book ever) and I loved the Ramona books as well and some of the older Newberry Books (Caddie Woodlawn, Roll of Thunder, Hear My Cry, The Door in the Wall, the Whipping Boy, etc). However, the only really good young adult books written in the early 1990s when I was growing up were Lois Lowry's Number the Stars and The Giver. All the rest, even the Newberry Books, were boring and tedious; so of course, all the little eight year old girls read the Baby Sitter Club Books, they were the only thing that was even semi-readable out there.
Today, JK Rowlings has revolutionized the youth market by showing publishers that children want to read well written books and getting more authors interested in writing children's books. The success of Harry Potter has helped revitalize the whole youth book market; even the Newberry Books/ Finalists are much more interesting and well-written than the books that they produced for my generation (Holes and Because of Winn Dixie for example).
As for the importance, I think that the Harry Potter phenom. is pretty important. Most kids would prefer reading Harry Potter to playing video games, etc. which in my eyes is a positive development.
Just kidding.
But seriously, you would be surprised at how derivative these books really are.