Some kids like school because then they can spend more time with their friends, and less time with their piano-addicted parents. Some parents feel like there child's musical ability is more important than them, so weekends are ruined with hours and hours of continuous music practice. My parents just take music too seriously, but I only think of it as a hobby. Sometimes they won't let me eat if I don't play 2 hours of piano, so yeah. I would much rather go to school every day.
I don't think that going to school every day of the week would be very productive. I know that people could learn more this way, but everyone needs a rest sometimes, and resting is good for processing the information that you've learned throughout the week. Taking away people's weekends would probably not make them very happy.
With the rising cost of living paired with odd packed work schedules adults in modern society can't be expected to attend school every day. I also think that because of how much students pay for their education in the first place they should be able to completely go online or attend "make-up," online lectures. It's just too hard to be expected to go to school full-time without big scholarships or loans because of the cost of living.