Nature expressly allows preprints. You can put your Nature paper on arXiv at any point, before or after review. Authors are perfectly able to open their papers themselves. Authors also retain all copyrights.

https://www.nature.com/authors/policies/license.html

I’m no fan of big publishing, but Nature’s policy is ok in this respect, and better than eg. IEEE.

> If people cared about Open Science, they'd publish in PeerJ or PLOS One, but they care a lot more about saying they have pub credits in Nature.

True, but perhaps the thinking goes: we'll publish another paper in an open journal, so we can have our cake and eat it too.

When I was an academic, the thinking was: if I manage to publish in Nature then I might actually be able to get a postdoc when my current one / PhD runs out. Otherwise I'll go open.