As with many questions about giving up (or not) versus retaining it, and why one should give it up in the first place, a criterion of something like "added value" is clarifying. In the first place, why "publish" with anyone who needs/wants to take the copyright from you? Duh, because those same people seem to have the power to grant status (nevermind the arguable business of "peer review"/correctness). Thus, from an economics viewpoint, many/most publishers are entirely happy to give you "status points" while making money by charging a fee for access to your work.
Naturally, as long as such publishers control the status-game, they will be happy to grant status while charging fees for access.
Naturally, there is an ambient confusion cultivated by for-profits about the supposed benefits-to-all of this system.
Naturally, in the short term, it is hard to generate status-points by "free" (but, therefore, mostly not "peer-reviewed") publication. (In fact, the very word "publication" in academia no longer seem to mean "a thing that has been made publicly available", but only something that has entered the formal peer-reviewed (and mostly corporation-controlled) "publishing" game.)
Now, yes, maintaining a web-site is not really "free", especially worrying about long-term maintenance. Filtering manuscripts even for basic sensibility is not trivial... It is a slightly pathetic form of "luck" that for most submissions to refereed journals, nothing is claimed that is sufficiently scandalous, or perhaps even widely interesting, to invite too serious skepticism, so that even if it's wrong or garbled, it really doesn't matter. In all that, and in light of recent years' journals' comments to referees that it's not our responsibility to verify correctness (!?!), but more "appropriateness for the journal" (this is about status), unless some alarm goes off about significant content... "peer review" absolutely does not guarantee exact correctness. Maybe ball-park correctness, on general principles of sense... which should be ok most of the time, etc.
So, for the time being, we are caught in a legacy system that had insinuated itself into the very fabric of academic function... and will be hard to surgically remove without endangering the patient, etc.
Still, some (especially not-for-profits, but not all not-for-profits!) are willing to negotiate limited-rights-transfers, ... which makes sense. But, even these days, one must speak up, or the default is that you surrender all rights, which is senseless.