Which also brought simple dungeons that are not a challenge and most bosses being a cake walk. Even the hardest bosses in Persona series don't come close to the bosses in devil survivor 1+2, SMT2,3 and 4 and DDS. Is it so much to ask for the gameplay parts that are not the sim parts to be fun and challenging like their past games? That won't take away from the parts that Persona 3/4 did good.
Also fusing is a element from SMT, should that be removed too?
What brought simple dungeons? The fact that Persona 3 became its own entity and not just a SMT knock-off like the rest of the off-spring? Persona 2's dungeon are hardly any example of intricate dungeon design. The entire school of Seven Sisters are essentially just the same designed corridors, the actual dungeons aren't any different from the other games -- They are copy-pasted blocks, doors and walls put together to make a big-pile of samey garbage. -- In retrospect, it's not in the slightest impressive at all.

Adachi's dungeon wasn't anything like the previous dungeons, neither was Marie's dungeon. So if you wanna make an argument that all the dungeons are the same then you'd be wrong -- I'm not that worried there won't be more variety for dungeons in Persona 5.
Persona 3-4 removed all the useless nonsense, it removed that retarded demon bullshit and also stupid random encounters so you'd no longer have to fear too much of having to engage in battle every 5 seconds. And of course, there's no longer as much need of consistent repetitive grinding, which is the worst part of any RPG in existence.
A straw-man argument -- Evidently, if I was trying to point out that Persona would have to remove all elements that would relate it to Shin Megami Tensei then there wouldn't be much game left now would there? Did I not specifically say "implement", which was meant as a word of phrasing, to contextualize an understanding that there is no need to implement more elements of the off-spring or the mother series (well not even mother since Shin Megami Tensei is another spin-off of another franchise) because Persona is not "Shin-Megami-Tensei" it's Persona now. And that's good because I like Persona because it's Persona and not Shin Megami Tensei. There's always room for improvement especially in dungeons, but it should not be any shape or form in similar style to games like Nocturne or those other spin-off titles. People are free to play and support those games if Persona does not live up their standards. It's that easy, really.