As the documentation says "Mathics will probably never have the power to compete with Mathematica® in industrial applications; yet, it might be an interesting alternative for educational purposes.". Moreover unlike Mathematica, anyone can examine the code, a definite plus for students.

that doesn't make too much sense because many, many universities already hold site licenses for mathematica where it is either free or very cheap.

Most students in the world are not at universities

All Raspberry Pi's have Mathematica licenses, so there's one cheap way in.