Could it just be that Square’s engineers are not very good? Large numbers of their good engineers left the company a long time ago. It may be they haven’t hired quality engineers to replace them. It could also be due to shit-flip floppy designers and producers.

Maybe, but I think it's more just poor planning and managing things and thats not fault of engineers.

Agreed.  In terms of technical skill, Square is strong as ever.

And they are using Unreal Engine 4, more or less as is, so there's not any weird customizations they've done.  The incompetence lie with Square Enix the publisher I believe, not the developers.

That's a producer problem, then, it sounds like.
I don't know the depth of the issues, but I do know that some of the Monolithsoft guys that came out of Square weren't the happiest. Mitsuda, who went freelance, didn't work with Square again for over 15 years. It seemed the big problematic projects were Final Fantasy 7, Xenogears, Chrono Cross, and Final Fantasy 12; and then almost everything else after that. Final Fantasy 7. Final Fantasy 7's 1 year+ delay, which seemed an eternity back then, seems minuscule today.

I wouldn't doubt this is the future for the Switch version.

My only hope is that Switch keeps selling good and third parties improves their efforts.

Why would it get cancelled?

Dragon Quest Builder came out on the Switch despite the PS4 version coming out 2 years before it.

I also don't believe it will be canceled.  But I think a lot of people  are going to be having flashbacks to the Project Cars type situations on Wii U.  A lot of games talked up for the Wii U were canceled.  Hell, the Wii U version of Project Cars was all the developers of that game would talk about for the longest time until they suddenly and unceremoniously canned it along with a tweet that basically gave the entire Wii U customer base a middle finger.  

Don't think that will happen here, Square knows money is to be made on the Switch version.  The bigger question is will they promote the release in any way shape or form or just drop it on the system silently and hope the customer base has the necessary clairvoyance to know it launched.  

Well, they said they wanted to push Dragon Quest in the west yet its western launch is three days before Spider-Man.  I know: 'different genres', 'different audiences' and you shouldn't judge a game's sales by one week, but that's not doing the game any favors.  If that's how they treat the western PS4 release then I'm going to half-expect them to release the Switch version in the same week as like, Pokemon or something with zero fanfare.