Hmmm.
If you own a house then you have insurance on your property in case it burns down, suffers subsidence, etc. You can live in that property for all your life and never claim (if you are lucky enough not to be blighted by ill fortune). Across the country as a whole, during that life of yours, many people will legitimately make an insurance claim though most won't have to.
The fact you might live in your house for years and never have a problem is NOT a reason to claim no-one needs insurance. I know of no-one who owns a property that does not invest a tiny amount of money in insurance.
Similarly car insurance.
Similarly home contents insurance. This is more pertinent actually. Your house is no doubt secure. You have the best bolts and locked fitted. You lock up every night and every time you leave home. Of course, you don't need insurance, do you? No one will EVER burgle you. They can't - because your hardware and processes are so good. Anyone who gets burgled is an idiot who has failed to secure their property. They deserve it.
Similarly for many that can afford it health insurance.
And now to WoW. Many millions of people play it. Thousands get hacked. The vast, vast majority DO NOT get hacked. This is not necessarily due to their cleverness and skill. It is statistical good fortune.
The Blizzard authenticator is merely an insurance (a very, very, very, cheap insurance) to protect a massive time investment in a game against foul play.
It makes things an order of magnitude harder for hackers to get at your account and ruin you fun. Note I do not say anyway it is foolproof, absolutely safe or anything else of the kind.
For all you poor misguided people sitting behind PCs thinking you are secure here are some facts to chew over.
1) WoW is big business - that attracts organised crime
2) What technology can invent, technology can circumvent.
3) Operating systems are mind boggling complex pieces of software full of bugs and exploits, discovered and undiscovered. A clever programmer might be able to use these to do just what the heck he likes on someone else's PC. Also all Microsoft software has "back doors" to allow snooping by government intelligence agencies. What other "back doors" might microsoft, rogue programmers, etc, put in there?
4) There is always a delay between a new virus/spyware/trojan threat and a fix from the suppliers of security software. This is a window of opportunity when bad things, like collecting user accounts and passwords for WoW might occur. As you may know - last month's microsoft update broke Zonealarm. These things happen. (Some idiot will now say Zonealarm is crap

)
5) People writing software to exploit Windows etc are a damned sight cleverer, more motivated and have greater resources at their disposal than you.
6) People ( that is salaried, bored, fallible, error-prone people) write, test and release security software, OS patches, virus updates and so on. These software products are not perfect. They are not bug free. The assumption that you are bomb proof because you have these packages and keep them up to date is not sound.
7) Potentially you need to just make one mistake that allows access to your personal data. To be perfectly safe you need to be perfect.
8) The arrogant assumption that you are safe because you are not an idiot and don't use a WoW account on more than one machine, don't share accounts, don't share your machine with anyone else, keep your OS and security software up to date, never visit dodgy websites (how do you know?), and so on may make you feel safe and smug. Sad souls who do not do these things are obviously making things easier for the hackers and are foolish. But this is not the only way account details are nicked.
9) WoW inside job - the easiest way for criminal elements to get your details is simply to bribe or threaten a WoW employee to assist them. This is not at all uncommon in financial call centres. Your precious PC security will not help much with that. As a matter of fact one reason the authenticator may fail is if a hacker asks a Blizzard employee to disconnect the authenticator from a stolen user account. It is to be hoped Blizz have put some procedures in place to make this unlikely to happen.
10) Well ....enough I think

For less than a the price of a bottle of wine I can make life very tough indeed for any potential hacker trying to get into my WoW account. The system used by the WoW authenticator is very widely used in commerce and industry and for good reason. Similar systems will become increasingly common in all online entertainment where login security might be an issue. In fact, I expect it to become compulsory in the next 5 to 10 years. Service providers like Blizzard will want to use the authenticator to protect their websites, games and services from malicious and criminal people.
oh and ...
11) The Titanic was unsinkable. They didn't bother to fit many life boats. There was no need. The passengers were all quite safe.