Account security is a serious matter in Azeroth. If a player's account is ever compromised, it can be a devastating blow. You work hard to reach the level cap, run the dungeons and raids for the gear your character needs and level your chosen professions. Chances are, you also have a fair amount of gold from questing, dailies, and your professions. If hackers gain access to your account, they wreak havoc while inside, stripping your characters of everything they have, taking all your gold, and selling anything of value.
My account has only been hacked into once, but it was more than enough for me to doublecheck my security settings, wipe my hard drive, and buy an authenticator. When my account was hacked, I was beyond devastated. All of the hard work I put into my characters was gone in an instant. Hackers move a lot like a fire.