It's horrid mechanic for casuals which makes me sick.
They could've given some normal HP regeneration instead.
Not to mention that each profession has a way of healing itself, making that idiotic regeneration even more silly.
Also, introduction of eating/drinking/whatever would achieve practically the same effect, but would at least make some sense and would make it feel better.
On top of that, it removes a lot of strategy from gamepaly since as long as you are alive, you can continue.
Take a look at Diablo 3, for example.
Instead of giving some idiotic Halo-like HP regeneration, they introduced HP globes, have HP potions and each class has a meaning of healing itself.
THAT'S how you solve those issues, and not with some idiotic HP Halo-like regeneration.