Most people that run these school systems are oblivious to the fact that: A) Kids are not going to magically become more literate by being forced to read some crappy novel B) Most kids don't even read the books they're given, instead relying on the internet (A.K.A. that thing that proved that school is 100% obsolete) to give them a quick summary of it, and doing their 5 page essay on that and C) Most kids would rather NOT think about school during the only time they have off.
It's almost similar to when they send you packets to do during Christmas Vacation, and you were too busy doing those to actually enjoy playing your new video game system (because homework packets make everybody feel jolly!). Except imagine them taking a bite out of your summer instead. That is what summer assignments are like.
Teacher: "Enjoy your summer. By the way, don't forget to write that 10-page essay and complete your summer assignment while the rest of your family is at the pool actually doing something fun!"