Let's look at how this RMAH affects hacking. It is important to first look at what the point of this game actually is. This game has 2 big things that define it, randomized dungeons and the RMAH. What this means is that the focus of the game is on finding items. Diablo games have always been a gear grind dungeon crawler. The actual game isn't that long, but then you get to farm bosses, make yourself stronger, and get better gear.
In D2 days, items had no value. How I mean that, is that there was no legitimate way to sell items, and as such in the designed system the items have 0 real value. This makes the game economy item driven, everything only has a value within the game. You farm items to trade for better items to help you farm more items. PvP aside, that is a big (some might say only) focus on the game. Dupers enter the picture and try to screw things up, as they always do. They try to control the in-game economy through duping and account hacking. With that control, they try to sell items online to give the items real value.
Now D3 enters the picture. Blizzard looks at the hackers from D2 and figures, if we legitimise item sales, then black market sites wont exist. If theres no point in black market sales then hacking wont be needed. That second line may seem odd to you, because its completely counter intuitive. By creating a RMAH, blizzard has given every item in the game an intrinsic value. Needless to say by legitimising the hackers end game, it promotes the steps that get there. Instead of saying "hacking is bad, don't do it. we will not stand for it" Blizz has basically said "Hacking is bad, don't do it. But if you are gonna do it anyways, we want a cut."
Seriously, blizzard saw what hackers did to D2 and came to the conclusion hey why don't we do that to our own game first? Well, suprise suprise the hackers are here too. The ONLY way a RMAH would be of any use is with a completely secure game. And as many have said, theres no such thing, hackers get into everything.
Now blizzards reply is to sell authenticators? This is like a win-win for blizzard. They see a problem and now not only is it the customers fault, but the solution is to give them more money. (Yes its a free mobile app, but not everyone has a smart phone)
GG Blizzard, well played.