So let's introduce healing over time...

Oh, I have rot now... Haha Larian!

It works in some games and not in others. It worked well in Dragon Age: Origins if I remember correctly, but I really don't think it would work here. There must be a fear for your characters' lives somewhere, too easy to walk through a field of mines with healing over time e.g.

And yes, it is one of the few things in the game that punishes you for having an unbalanced party (i.e. no Cure Wounds/water magic) and I'd personally prefer it to stay.

Healing Rain sounds cool. But I'd prefer if it healed everything in the area (because I'm masochistic and I hate zombies).