That's bullshit. Universities and professors have all the power; they just choose not to use it. The journal name means a lot, but so do the names of universities and well-respected researchers.
Certainly they can. What's forcing you to publish in nature? Just like... don't. If someone down the line is judging you based on what journal your work ended up in and not the quality of the work... well you probably don't want to work with them anyway
Not trying to be snarky here -- genuinely want to know your perspective. As an outsider, everything I know about it leads me to believe that academia is so competitive that you really can't afford to just "not publish in top journals" and be picky about who you work with/what offers you take.
Academic managers force you. Your older colleagues force you because they are part of the game. However, it is possible to work in academia and not to bend.
Anyway, make your research available, no matter where you choose to publish it. Take a look at DORA http://www.ascb.org/dora/ and popularize this declaration among other researchers. Help your colleagues who don't know how to find an article fast.
They're not going to fix the problem alone, and if they want to switch universities later they'll probably take a career hit in impact factor. But that's still very different from the postdoc/adjunct/non-tenure-track case where people who buck the system don't get positions, and so no one can sustainably push back.
Tenured professors generally care about the grad students and postdocs under their tutelage, which can push them towards submitting to a closed journal.
I think you miss the point. If there is one journal that specializes in your particular field, what else are you supposed to publish to? And if you aren't publishing to somewhere that your colleagues read, you aren't producing meaningful science.
Particle physicists did it, though. They managed to organize. If your field has one Elsevier journal to which everything is published all the better, because that means an alternative will be easier to promote with emails and at conferences. If your field is small, coordinating a shift away from journals is easier than if it is massive.