Well cannot speak about the editor because I only made crappy stuff with it.
concerning respawning, well honestly what I like in Larian's game is that they always have hell of a story to tell and wiping an area is part of the story, it is like in the tales, when you kill someone it does not come back (well at least if we take apart ghost and haunting). I'd rather like to believe that each and every monsters are unique somehow with their own story (that I will brutally bring to an end) than bashing common monsters just to get a level.
about level scaling, and this is my own opinion, I really think it sucks, I mean where's the point, where's the epic battle when you can kill a powerful necromancer with a crappy stuff and two skills?! I like to see my guyz starting from killing rats in a sewer as common people to become more and more powerful and then, and only then, being able to slay legendary creatures. Where is the fun when every peasant can kill the ultimate boss of a game?
