I just checked my profile and I saw that my facebook e-mail address was shared with 'only me', likely due to other privacy choices I made and that it stopped sharing my real e-mail address. I think this might have had the effect where people wouldn't see any e-mail address shared. (Although one can easily derive the @facebook.com e-mail address anyway.)
Also, this change just generally makes it harder to make use of other social sites. Need the person's e-mail address to add them on LinkedIn? Need to scrape e-mail addresses of your friends to invite them to another service (as was talked about a lot a few years ago)? Can't do either in many cases if your friends just show their @facebook addresses.
Edit: Well, for LinkedIn that would only work if the person associated their facebook.com address with LinkedIn, which I don't think people do. For the latter, it could still work but the person would strangely hear about the other service via Facebook (which I suppose Facebook could 'lose' those messages if it became a problem) and it could be hard to look people up by their more common e-mail addresses.
Also, this change just generally makes it harder to make use of other social sites. Need the person's e-mail address to add them on LinkedIn? Need to scrape e-mail addresses of your friends to invite them to another service (as was talked about a lot a few years ago)? Can't do either in many cases if your friends just show their @facebook addresses.
Edit: Well, for LinkedIn that would only work if the person associated their facebook.com address with LinkedIn, which I don't think people do. For the latter, it could still work but the person would strangely hear about the other service via Facebook (which I suppose Facebook could 'lose' those messages if it became a problem) and it could be hard to look people up by their more common e-mail addresses.