In a game that is focused on the economy and crafting having a duping exploit go for any length of time unchallenged is... not good news.

Even if they plug the holes, the exploiters already piled up resources and probably spread it under several items and they can now tickle it down in the game... or just sell it for real money.

Exploits and cheats are a common part of online gaming now and I admit it's one of the reasons I'm not too keen of playing any online game, especially permanent ones.