What are the pros of school attendance being voluntary?

Oh gosh- that side is a toughy. I would say a pro is that people will have to create their own self-motivation. The ones that succeed with this will always have the drive to success. The ones that fail early on, ultimately would have been the highschool drop outs, etc. So it is better to find out early on, so the schools can focus their efforts on the kids that care. I am not so sure that is the right angel, but it is all I could think of.