It's all about the balance. It doesn't matter that you're recovering 15k HP/sec if you're losing 20k hp/sec. You're still going to die in 11 seconds (with 45k HP). Of course some skills tip that balance in your favour (Serenity, Revenge, basically healing skills) - but you got the idea.
Add 1-1.5k armor and 150-200 resistances there and you should do a lot better. Maybe instead of that you could get something like 800 LoH. Who knows, maybe even both
Yeah, I know, that's not easy (or nice), you might even have to give up some dps, but that's how the game works