"Open Access": CC-BY licence Why would a scientist or mathematician want to publish a paper under the Creative Commons CC BY licence?  This licence allows the work to be modified.  Why would you want to allow a scientific paper to be altered?

Yet Arxiv at https://arxiv.org/help/license seems to offer only licences that allow changes.

Similary Nature Communications at http://www.nature.com/ncomms/about/open-access:

"Nature Communications articles are published open access under a CC BY license".

The CC licences that do not allow change are the ones with ND (no derive). So the natural choice would seem to be either BY-ND or BY-NC-ND. Can anyone shed light?
I work for a literature archive, and this is a very important question for me. Here is an example of how restrictive licensing affects our work. We host a large collection of biomedical publications. We developed a tool that identifies mentions of research data in the text. The tool highlights these mentions for readers to find it easier. If the article is licensed as CC-BY-ND (no derivatives) we cannot display the highlight, because it changes the article.
We are a publicly funded, free service that offers free open tools for researchers. But we can only develop new functionalities based on public data. The more restrictive you go, the less value we can provide for the benefit of all.