Nature only gives me ris-formatted citations, but I use bibtex.
Also ris is far from human readable.
ris can be reformatted to bibtext, but doing that manually disturbs my workflow when getting references while taking note about a paper in emacs.
I tend to search online for references, often just using google scholar, so when I find a ris reference, the first data I get for the ris-citation is a link.