The reason is simple. Like 98% of the player base shows that they don't want long, confusing dngs with gimmicks on how you progress or optional paths. With makes sense, this game has a hella-alot of dngs ... imagine each of them having some the paths and gimmicks you had to remember from the ARR dngs. People will be very annoyed if you ask them to remember the unique design and gimmick of all these dngs. I know this cause I acknowledge that I refuse to touch most older dngs for this very reason.

It's kind of a pie-in-the-sky idea to want them to release as many dngs as they do AND make them more complex than tunnel mobs -> boss. Not cause they can't do it but because most people will simply FORGET how to run them. Liiike ... sure, if there were only 20 dngs in this game I could see them being more creative. But I'm not jumping at the chance to get lost in 70+ unique set ups. Most people see dngs as a pretty looking chore you do for glam and tomes and the devs noticed this and reacted as such.

Want more complex dngs I think asking for more Eureka and HoH is your best bet.