>>54270094Dungeons in RPGs in general have mostly died, not just in Pokemon.
1. They're harder to design.
2. Reviewers who review on strict timelines might get pissy about the extra time "wasted" in the dungeon.
3. Kids get lost/bored/confused.
3a. Reviewers get lost/bored/confused.
4. They're harder for players to manage supplies in, and most modern gamers whine about that.
5. More twists and turns means more geometry, textures, and such, which requires more work and more hardware power.
6. People will just look up maps online instead of actually exploring it anyway.
7. They tend to stink if you replay the game and have to run it again, or die partway through and have to run it again; something playtesters and focus groups definitely aren't fans of.
Even if the dev is willing and able, and aren't bothered by these things, it still means extra work trying to figure out how to make a dungeon engaging and/or fun.
At least with puzzles, puzzles died because of the internet's ability to spoil everything instantly. Dungeons died because gaming as a whole has been 99% taken over by people who just passively play shit without caring about it, people who would unironically not give a fuck if a Pokemon gen ended up being a wide hallway
(oh wait, that was gen 8.) 
