"I am for one ok with propriety software... What I am not ok with though are monopolies, lock-ins and influencing education."

I think one important point is that closed-source proprietary software inherently implies lock-in. Some portion of proprietary file formats are crappy bags of bytes because the company wants a lock-in and some portion are that way because of simple laziness and you can't easily sort which.

The other thing about people using matlab is that society at large, the scientific community and such-and-such large groups pay the price of crap being caught within matlab and whoever writes the original code can just move on.