Considering they have chosen to lessen the amount of dungeons made per patch, I do not think it's realistic to expect more complex dungeon designs unless it comes at the cost of normal MSQ dungeons, which might be problematic for some. I also think the devs are content with how dungeons are used in this game, and its current and future design would only be to ensure the continuation of its current usage, unless they see a benefit to change the status quo.

And on a personal note, I don't care for optional enemies/rooms regardless of the reward. I want to be forced to full clear the dungeon, regardless of difficulty.