Heck people seem to dislike the "eat food to regain health" system that's already in place...
I mean, they dislike it for the exact opposite reason a more elaborate rest mechanic would be welcomed, so it's quite weird that you are equating the two.
What the OP is asking for it's basically what Pathfinder Kingmaker already does. It's a lean simple and yet brilliant system... But it makes sense only if your game makes traveling in the world map a significant part of the experience, which doesn't seem to be the direction where BG2 is going, so far.
