  We have it because, at the time, school was a really good idea. Hell, back then? It was a great idea. They taught you what you absolutely needed to know to be "educated", one 'o them "smart folk", say. Now, since America is such a communist state, manipulating the lives of all of its children, they've inducted this "policy of higher learning" used to make us "well-versed" in every aspect of knowledge. While it might be a good idea, some people just don't give a shit ( see, for reference : Josh Chandler) about that other stuff. Teaching style has never been that great, either. They seek to teach, not to imbue, us with an idea.
I find it to be the mark of a true teacher when you can apply their ideas to your own life versus reciting all the facts and psychobabble within each subject by rote. That kind of screws math, but...it's math. It's all conceptual when you get high enough up in the ranks. Plus, I don't like it. I can do it, but I don't like it. Irrelevently yours. What a post, just to one question. 
