Should it be illegal for students to drop out of school?

I think that it should not be illegal for a student to drop out of school, but I do think that there should be some limitations as to why the student is dropping out. If a student needs to get a full time job to support his or her family, then that should be okay. But if a student wants to drop out because they just don't want to go to school, that shouldn't be allowed. I think that there should be a valid reason as to why the student wants to drop out. In Iowa, the legal age to drop out is 16. I think that this is okay, but, like I said, I think that there should be some limitations.