Its not the difficulty increase for me, that I get.Its just that it has insufficient novelty.

The mist mechanic - OK but not super exciting.
The Boss is in a dungeon? - OK that's new and suspiciously smells like a reaction to the ways ingenious players have cheesed previous Bosses not a new mechanic.
Non Hostile Dverger? - About time - oh wait we have to slaughter them to progress Ho Humm
Dungeons with quest objects - Yes well what Biome hasn't? (Rhetorical - Plains doesn't instead we had a new mechanic of Tar Pits) Mistlands is back to plan A
Tough and different enemies? - Yes well same as every Biome

Yes I know it carries on the established way of progression but somehow just doesn't catch my attention rather amp my personal difficulties and start a fresh than bother after giving it a few dozen hours..

But I tell myself "EA" and enjoy what does catch my interest. The game still has much appeal for me just not in the Mist