Back when I was a teen I used to fraud people and scam ebay sellers through paypal. If I were to somehow gain access to an email (via RAT, Cookie hijacking), one of the easiest ways to recover a password was to look for a provider that sent out a plaintext password. Chances are the unfortunate target used the same password on every site (or if it was lowercase and alpha, that password + "1").

That would grant continued access to the email, and other sites that took protection a little more seriously like Paypal and Bank Logins (you can't reset a Paypal password with just an email, and if you could, such an action would make Paypal fraud detection software go nuts).