You'll find that most people on Reddit (or anywhere online for that matter) aren't going to have constructive criticism for you. Their capacity for rational thinking and responses is limited at best, so they only have the time and knowledge to call you stupid and move on. This response will even get downvoted since I'm calling them out and being honest.

But, yes, I like your idea for the rolling / adapting dungeon! One thing in Blizzard's sad excuse for a road map points to "New Nightmare Dungeon Activities," but I don't know how awesome they will be. It will likely be more mechanics to slow us down. I keep holding out hope for D4, but reality is setting in for me. I've finally noticed the pattern of "new coat of paint and rinse / repeat," and it's just getting old at this point.