I can think of a lot of courses that *should* be required. The good thing about philosophy is, that when properly done, it can help in developing basic logic skills and critical thinking.
The problem is that you need a teacher that has some background in philosophy and has some critical thinking skills themselves. Unfortunately, this is less common that we would like.
I also think some basic computer programming skills should be required with the goal of learning how algorithms work and how to develop basic programs. That would also increase logic skills and debugging would help in critical thinking. But, again, it requires teachers that have the skills required. Most do not.
And, let's face it, any real philosophy course would lead students to challenge the beliefs of their parents (even more than they already do), which would probably nor well with the tax base. Let's face it, most parents don't have critical thinking skills and really don't want they children to either (no matter what they say).