I’ve never understood why we need emails in papers.
Who sends emails to paper authors? How often do they respond? How fast do the email addresses go out of date? I lost access to my email address included in most my papers within 2 years of publication.
I see little to no value to have it included in the paper.
I do email paper authors and I do respond to requests and inquiries about my own papers. Even if you don't work at the same institution any longer, most universities let you redirect your email for many years after you left.
Also, I don't think we are yet at the point when human2human communication is not possible.
I do, when I'd like to read a paper that's locked behind a paywall and not available on sci-hub. Authors of scientific papers are much like any other authors... they want to be read. The more enlightened among them understand that obscurity is a problem rather than a perk. They also tend to appreciate engagement in the form of follow-up questions (at least from people who actually read the paper.)
Obviously it's not a major concern on arxiv, but in a larger historical sense, this type of communication was a key original application of email.
If an author wants to be read then they will keep the preprint PDFs on their website (along with their current email address). An added benefit is that Google Scholar indexes and links directly to the PDFs instead of the publisher website.
