[masivemunkey]

I think you may have a unique case on your hands. I am a web developer for a big eCommerce site and we use emails to identify users (we switched from usernames to emails after a few months of testing actually). After three years of the site being up we have only had a handful of people get confused about their email changing.

If a user does change their email they can log in as their old email and simply update their account to their new one.

Email is a much better system than username because people constantly forget the unique username they created for that specific site. You don't really forget your email very often.

[th5]

+1 to your decision. I HATE site that use usernames instead of emails... i wont even use sites that do that unless i really really have to (like my health care provider).

[imissmyjuno]

There is typically nothing stopping you from using your email as a username, though. I like the freedom of using either, to be honest.

[kerneis]

Except for the many, many websites that have stupid restrictions like: "sorry, your username should be lower-case letters only".

[beaumartinez]

It's not necessarily stupid—it could be so that your username can be included in URLs (like Twitter). "Lower-case only" is stupid though.

[martinced]

The problem is not displaying a username. The problem is using the username to login. Because users forget that.

If you're stupidly using your email as your username then your email becomes public should the site you're on show, at any point, your username.

Which is why sites correctly done use the email for login but display a username and never your email. Correctly done sites also forbid username from containing '@', so that you can be sure that people don't do anything retardedly stupid like using their email as username, which would be displayed publicly on the site...