I don't remember changing anything in my profile for years and after logging in it looked like this:
[ ] Full public profile
[x] Community profile
So apparently not enabled by default. While I don't condone such changes at all, I can't really complain. The mail is not overly long and the profile stuff is visible above the fold. Might be different for non-EU people. But yeah, I might have missed it if I hadn't been warned.