My cleric is experiencing this. I'm as fully invested in threat reduction as I know how to be and it's still a huge problem. Just died in the final boss fight earlier tonight due to it.
The guild is growing by leaps and bounds and the game isn't even open to the public yet. I've already had some crazy fun dungeons runs with these guys while voice-chatting on Mumble.
Open beta started early for people who bought packs. HotN got in 5 days early. GoN got in 3 days early. It's tomorrow around Noon Eastern for everyone though. I'm having a lot of fun so far. Lvl 22 Devoted Cleric.