Why can't a dungeon be designed from the perspective that it might only be ran a handful of times by any one individual? Why do they have to be designed with the intent of being glorified hamster wheels that occasionally give us loot to keep us running on the hamster wheel? Give me one reason for the hamster wheel's continued existence other than to slow down content consumption. Just one.
When the goal is to keep us on the same hamster wheel as long as possible, by all means we are going to find the best way to be as lazy as possible about getting that wheel to turn just enough to hand out the rewards.
You mention you have to have an open mind to find creative ways to keep people engaged in the linear repetitive dungeons, aka the beloved hamster wheels, you also need an open mind to find the creative ways to encourage people to get away from the hamster wheels that so many MMO's have conditioned people to crave as well.
Going back to the RPG roots of pen and paper, one of the first things any GM/DM learns is players will do something you won't expect and never even thought to plan for. When that happens, one of two things happens... the GM/DM essentially crashes ending the session/hard vetos the player's choice, or they roll with it. The ones that roll with it, also tend to be the ones that are fun to play with as they can handle people going off script. The other ones, good luck as unless things go how they planned it... things can get dicey for everyone quickly. But you also have to think about what beyond just wacky unexpected player choices let them do this kind of stuff. Its all the tools they have available to them.
This was said in regards to CC earlier in the thread.
I guess Repose doesn't count as CC anymore. All healers have that. Tanks have two. A stun and an interrupt. Melee DPS all have a Stun. Ranged DPS all have a Bind and an Interrupt. BLM has an AoE sleep. Only ones left out are RDM and SMN, but those also have the added utility of being able to back up heal and raise instead which are just as valuable.
Where the problem comes in, is some players got clever and figured out that certain dangerous enemies could be kept CC'ed for extended periods of times, and some devs didn't like this. Which resulted in a lot of CC immune mobs, in addition to gradual resistance buildup, out side of very, very specific ones. Essentially taking away part of our problem solving toolkits.
So that left us with essentially two options, avoid the mobs or kill the mobs. People went with the avoid the mobs first. Devs didn't like that either so they put up gates that would not come down unless we killed the mobs first. So now we got a singular tool left. Kill the mobs. We have one tool with which to approach the problem, so we found the most effective way to apply it.
This stripping of us players to one effective tool is what resulted in the current design. We adapted to having one tool. Unfortunately, for more involved dungeons, we will need more effective tools available to us. And unless we get more tools, and dungeons developed with the consideration that we might do something unexpected, all we will ever get are hamster wheels.