I think that the reason literary analysis is overdone in high school is that it is really the only academic subject where a student can have something approaching an original idea and then defend it using textual evidence (from the work itself). As long as whatever the idea is can be supported with evidence, it's good to go. That it's really just a load of BS isn't relevant.
Despite what K-12 educators want to think, this generally can't be done until graduate school in the other academic disciplines. There is simply too much background knowledge needed to produce original work. Generally the undergraduate years are devoted to obtaining that background knowledge.
