Pretty generally they have no investment in their character and thus do not care in the slightest if they die.
The way they balanced it before, and how it worked, was by making it require investment to be annoying, and the more annoying things required more investment. Thus in order to truely annoy someone, you had to invest time and effort into your character.
And while i have no idea if its working that well at the moment in haven and hearth...
I certainly saw it work first hand on a small scale in haven and hearth in previous worlds.
Now while i'm not argueing that small scale is the same as large scale, however i meerly want to say that theirs no reasons to assume that its going to fail, provided its engineered well. And given Jorb & Loftar pretty much approached H&H as one big social experiment to find things like this out, i would suspect they have a better shot at achieving this then anyone before them.
I might guess that it will still have lots of problems and griefing if it gets popular, however i must strongly state that there is still a freaken chance it will work out, and that some ideas are worth a bit of risk.
//I may be a bit fustrated at some of the negativism in this thread, while no doubt a lot of it is based on fustration at mmo's going horrible wrong, we gotta keep a little hope alive folks and admit that theres a chance things might work out, and sometimes thats enough reason to support something.