There was an interesting discussion on the WTM Boards of books that people were assigned to read in high school. The lists were pretty typical, but what I found interesting was that most of the posters seemed to think it was a negative thing to have little assigned reading. If they literally were not required to read much of anything, then yes, it would be a bad thing.
But I think it is a good thing to have few books that are specifically assigned. I think it is much better to have a list of good books- there are plenty of good books out there- and to leave the decision up to the student. This was what my teachers in high school did. We had few books assigned, but we had plenty of reading required. I chose books I thought I would enjoy, and since there were guidelines, I was introduced to new books that I might not have read on my own.
I've heard far too many people say that they hated the books they were assigned to read in school. We can encourage plenty of worthwhile reading without being quite so specific.