As a dungeon runner...

[Jojoya]

Which is why having more than one released at a time helps. Keeps it from feeling too pointless after you get whatever you want out of it. Having 2+ at least keeps it from going stale immediately.

But it's still pointless once you have what you want.

You could always be running some of the other 60+ dungeons in the game if all you're after is variety in dungeon running.

Its honestly cause theyre too linear and straight forward. No matter how pretty they look, boss mechanics and direction of dungeons is literally a gauntlet of enemies. Big pull to first boss, Wipe out stuff. Boss fight. Big pull to second boss, wipe out stuff, Second boss. Etc etc.

They need to sit down and think about design mechanics. I think one thing dungeons need to offer is variety of completion - either multiple paths with separate rewards per path that youre RNGed into (to prevent people just min maxing and selecting hte same path over and over), puzzles or challanges built into the dungeon that require something more to do than kill stuff (jump quest where 2 people in your party need to complete it to unlock a path so you all can proceed forward), challange bonuses for the dungeons (Speed clears, No deaths, dont use items, has to be synced, etc etc.) that feeds into a possible weekly ladder challange for things like MGP or bonus materials. Such as all runner ups get 10k MGP, while first gets 50, second gets 40, and third gets 30k MPG or possibly rewards kind of like how Khloe's journal operates. Or how about bonus mini bosses that are spawned when you complete certain objectives for the dungeon.

There's a lot they can do that can add variety and interest to dungeons, but they need to actually do it. Only thing I foresee being a problem is players will get pissed and say "It's to hard!" and whine.

Those alternate designs don't work in practice when players are primarily entering as a random group formed through a Duty Finder roulette.

Most players simply want to get in and out as fast as possible with their tomestones and whatever loot they manage to get. They aren't interested in exploring or taking the path less efficient. They're going to abandon duty the moment they find they need to complete a jump puzzle to progress then complain loudly to SE that it was stupid to add in jump puzzles when people who like jump puzzles already have Leap of Faith and the sightseeing logs.

Creating such dungeons as you suggest ends up a waste of developer time and resources when so few players end up fully utilizing them.

I know that this is the point some people would go "but Savage and Ultimate!". Those are mostly reused assets with a few graphics tweaks and new mechanics added in, something that takes relatively little time to accomplish compared to creating a complex dungeon from scratch.