Or when you enter bad login info, and the site doesn't tell you if it was your email or your password. But on the reset password form it tells you when you put a bad email in.

I was not talking about retyping the new password, but about requesting the old password before you can change it. The reason you do this is because even if you theoretically could hijack the session, you still can not hijack the account. But the priority seems a bit off when the password is more important then the account, which makes you believe that the people behind the sites only added the extra password validation because they seen it every where else, and not because they understand the principle behind it.

It is a protection against typos, because people are lazy and error-prone and it matters because getting it wrong means email delivery fails, whereas a misspelled name is no big deal.

So, elegantly, two different issues use the same simple solution.

It does seem that way when you're a skilled typist, but I recall reading an article about a year ago where they discovered that forcing the average user to re-enter their email significantly improved their rate of invalid emails (e.g. not detectable by a regex, like jhonsmith@gmail.com or johnsmith@gamil.com).

A feature like this should probably be considered based on the expected type of user vs. the convenience of signing up quickly. Non-technical users where there isn't a significant dropoff from the signup form => probably a good idea.