How Effective is School?

I saw a music video on Youtube which made me think about how much school actually helps us. Elementary to high school especially, where we don't really get to choose our classes.
I've thought a little about this, as I designed schools for my worlds. For example, in my fantasy worlds, students wouldn't need more than the basic math, and biology and such. If they needed to learn about advanced chemistry or such, they would take more classes on the subjects they thought they'd use. They also don't have technology, so a lot of stuff would be pointless for the majority of then to need (no computer classes for them @_@ )

Compared to our schools here... Where we learn calculus for a couple years in high school, and then never use it again and forget all of it before you finish college.
And spend four years analyzing literature.
Or learn a language that you'll never speak once you graduate.

Now, the basics of biology, math, psychology, ex can be very important. It's great to understand how life works, and to understand how the mind works and how to take care of it. And there's definitely plenty of literature that is worth looking at, especially if it teaches you not to believe everything you read without examining it first.
If you want to study in a foreign country, then definitely learn French!
But you shouldn't be forced to take more advanced classes on it if you know you're never going to use it. If you want to be a preschool teacher, do you really need to know how to combine acids, or analyze the symbols in Lord of the Flies?
Especially when you could be learning how to give first aid to someone.
Or learning how to deal with taxes, find housing, and take care of kids.

There are so many important topics about living in the modern world that I knew absolutely nothing about when I graduated high school. You'd need to pay to take separate classes to learn about first aid (something I'd very much like to learn).
Or you can ask around and look on the internet for information, and risk learning false info.

Why are some subjects forced onto students when there are so many important things that we need if we want to live in today's society?

Then again, there's a lot of really pointless stuff in today's society... School is just an easy one to pick on. --_--