During the Switch's lifespan, they release two new expansions for DQX, and DQX offline base game + DLC. The problem is the west is not getting those, but it's not like the DQ team is not productive.
The Builders series were a huge success and DQ Treasures and Monsters 3 were also very well received, they're just not gonna set the world on fire, they're smaller games by definition.
Infinity Strash bombed commercially and critically but afaik it was mostly an externally developed game as Dai is more its own thing.
New numbered titles have always taken long to develop, personally I believe that has more to do with Horii preferring to have a smaller team to have more control over things rather than than mismanagement. There's no denying something went wrong with DQ3 though, but I don't think that's become the norm.
They're surely having some trouble right now, though, with 2/3 of the main creator trio gone, so maybe that Nier guy is being put there to help on that front.