This is a move which some people expected for a while. It is about the fact that who has the copyright is less relevant than who can enforce digital management rights.
A while ago I got interested into that (see the post
and made a list of moves by publishers which may be seen as related to the one made by Nature.
So it’s a trend. It looks like academic publishers just discovered what everybody else discovered before: the power of DRM.
I guess that people listening to music and watching movies form so big a population that we can say they define the average level of human intelligence.
These moves show that publishers (and your average academic boss) believe that you, researcher, are more stupid than this average.