Agreed that having a way to consider mobs is a good thing.
Since almost every other 'difficulty' setting is a toggle, just implement it as such so those who don't want it can have it turned off. Even make it one of those permanent choice per game toggles. Then everyone's happy as they can play their single player game exactly the way that they want to.
But even just a simple 3 levels of 'way over your head', 'you may or may not live', and 'you would crush it' set of buckets would be good.
The bear you get some warning from the nearby NPC, though you don't have a frame of reference yet to know whether you're 'special' and therefore much stronger than standard NPCs in the world. The temple in Gilded Vale though very quickly gets significantly more difficult, so it sucks you into thinking that you're capable of it and then smacks you upside the head suddenly.