As long there are people buying gw stuff from ebay, hacking accounts is big business. These arent inviduals who hack accounts but well organized crime organisations. The same people who tried to rob peoples online bankaccount discovered that is a lot easier to steal virtual money from populair games and selling it on ebay, than to steal real money. As long as it isnt real money nobody will hunt those criminals... What can you do when your account gets hacked? Can you go to the police and tell them that your gw cash has been stolen?? I think those cops will laugh at you...
Another thing is that a few weeks ago chinese police discovered a house full of kidnapped teenagers who were forced to farm 12 hours a day (WoW)... without a break. Their "boss" sold the money on ebay.
As long people keep buying gw/wow cash and other valuables on ebay this will get worse and worse (again, police does nothing, anet does nothing and many people dont give a sh*t.... as long as their account isnt hacked)