Not a bug. If you're worried about security as a user, d/l the free authenticator. If you're worried about Blizzard, don't -- they're big kids. You can run your 10+ million user game platform the way you want, Blizzard will run theirs the way they want.
Just like how we shouldn't worry about big kids Sony and their 70+ million network being compromised? Telling people not to worry about security works until they, inevitably, have their data compromised. Technically aware consumers have a responsibility to put pressure on companies to be secure with information.
"Technically aware consumers have a responsibility to put pressure on companies to be secure with information."
No one's shown that Blizzard has been unsecure with anyone's information. I see a lot of people running around like the sky is falling when it's not.