Problem is that many people today do still mistake Free software as no cost and for good reason. Funnily enough, "open sourcesource" turns out to have great SEO. Free software doesn't.
I'm not especially good at this, and obviously 'free software' has the benefit of a few decades history among the people who actually know it. But almost anything seems better than a phrase which has a very obvious meaning that's not the one you meant, and the consequent need for fussy little explanations. Especially when most Free Software is also free software.