So there should be absolutely no consequences for doing poorly in combat?
The consequence of doing poorly in combat is losing combat.
There's so many ways to get back to full HP after a fight at no cost and so many bullshit ways for the game to kill your party even though you'd survive otherwise(like running through fire to get back in formation) that it's simply a case of bad design not to have all the harmful surfaces cleared and damage removed immediately when the fight ends.
Therefor, always being at 100% HP out of combat is a bad idea because it removes challenge and strategy from a large number of things in the game. Such as back-to-back encounters, or traps.
Divinity does not have any back-to-back encounters, if a new wave of enemies is meant to arrive without giving you prep-time, it'll do it within the same battle.
Almost all the traps in the first D:OS would either kill you immediately, or destroy something of value.
There rarely was a case of a trap failing to serve it's purpose based on your current HP.
Basically, none of those are issues of balance, but rather issues of design.
