I am guilty of publishing in paid journals as well, but it's kind of a trap for my area of research. Well, not really a trap, but we would need critical mass on switching over. (Though, it's pretty common in our community to post the papers on our websites, "illegally"- which you can find with Google Scholar) For us, conference proceedings are more important than journals; but, to give a talk at the important conferences, that are sponsored by the publishers, it ends up in the publisher's journal. As it stands, to be seen by others in the community, we need to publish in these journals and conferences. Not to say that we couldn't do it, it would need inertia to switch over. Yes, it can be done, but it won't happen over-night and I get that it starts with us.