Earlier quoted context omitted.
I'm confused by this. The researchers don't get paid for their paper, and it seems like the peer reviewers don't get paid for doing the peer review: http://www.nature.com/news/open-access-the-true-cost-of-scie... So why exactly are publications locking these papers behind massively expensive paywalls when writing them and reviewing them are being done for free?
Because they can and academic scientists don't do anything to change the status quo.
As a grad student, one basically doesn't have much say. Postdocs have a bit more latitude, but need to "play the game" to land jobs; pre-tenure faculty are in a very similar position if they want to keep theirs. Even tenured PIs are in a pretty precarious position: many are on soft-money positions (no grants, no salary), all of them need grants, and their trainees also presumably want to move up the grad student -> postdoc -> faculty ladder.
Getting this to change is a massive collective action problem and it's really going to need a push from institutions and the big names at the very top. This holds not just for publications, but a lot of other issues with academia too. I'd love to spend more time making our code solid and publicly available, but there's essentially no payoff for that either.