As ticked off as people are over this, though, it’s more annoying than malicious.
The email on your profile recently was set by default to your Facebook “email” address, which is your username@facebook.com. This simply sends emails directly to your Facebook messages. For people who don’t want to give out their email, it’s actually fairly useful. It’s how Facebook handled all of this that’s turning out to be a mess.
Essentially, they did this without offering any warning, explanation, or justification. While you can’t get rid of the email address, getting it off your profile is relatively easy to do, for Facebook: go to Privacy Settings, click Timeline Info up at the top (it’s a link in a paragraph), edit your Contact Info, and use the dropdowns on your Facebook email to hide it on your profile and configure it so only you can see it. That will essentially remove it from the site.
So why did Facebook even do this? To increase site traffic, essentially. If people trying to email you send you a Facebook message, that’s one more precious page view for it and another stolen away from its competitors.
This is just the start: expect more annoyances like this in the future. Zucks gotta prop up that stock price!