I definitely get the impression that Wolfram builds his tools primarily for himself, and is happy to let other people play with them because that way he gets money to pay for them.

That is not the impression, that is exactly why, And actually that is their strength. Back in the days the whole Apple was there to make software for Jobs and look how awesome that turned out. Wolfram is trying to complete tue work of Leibniz and create a universal calculus. A unifying language for symbolic computation, which is amazing.