@LUIGITORNADO this will be a bit of a lengthy response but that content is unlikely to ever come to PC simply because of game engine stuff.

PC/PS4 DQ11 was developed on an older version of the engine that didn't support Switch development yet at the time. To port the game to Switch required a newer version of the engine for which everything had to be basically remade/readapted which(despite being based on the same visuals) more or less functionally make the Switch version as close to a full blow remake of the 2017 Japanese PS4 and 2018 western PS4/PC versions as can be.

That means the later can't just "patch in" the newer content without basically porting the Switch version all over again to these other consoles because the newer content was made under the newer game engine rather than the old one which earlier versions's coding/etc used.

Add to the fact that being ported to the new engine was so it could release on Switch and that the Switch version is being published by Nintendo themselves in the west rather than Square Enix, it adds chances that the new content might even have been partly funded by Nintendo themselves to make up for how late they got the game on their console. So right there you may have financial-incentives ontop of the engine stuff behind this being Switch exclusives for the near future at the very least.

Also as to why playing this on an handheld rather than a PC... that is very much a market thing for jRPGs which was influenced by Japan but not exclusively so.

To put it simply: with long play-times running in the 50-100 hours the market(even if there are exceptions in individual players) for jRPGs(that is, beyond exceptions such as Final Fantasy and Persona) had been moving away from traditional home consoles for a long while. Simply said most players with the funds to keep up with that sort of games also lack the primary ressources to play them: time.

The transition to handheld thus happened a while back because devs noticed that the average people who used to play jRPGs at home hadn't moved away from RPGs as they got older. It's their context that did and they also realized that, when available, they still continued to play them.... on handheld, while commuting to work in public transports such as subway or public bus. Or during lunch breaks/etc.

Basically whenever they could find a bit of time thanks to handheld convenience since home life generally didn't leave them that much time to sit in front of an home console which probably further helped the primacy of games like shooters and such on home consoles since they required a much lower "time investment" from players.

We're seeing a slight resurgence of jRPGs on home console through stuff like Persona 5 but so far they're still primarily outliers rather than the norm. And there's still people, even ones with PS4, who're still hoping for Switch ports of stuff like Persona for the reasons stated above(not enough time to really sit down in front of PS4 but plenty of commuting to work/etc during which they can play on an handheld).

Now that was a bit of a tangent i'll admit but that was so I could explains why even plenty of working professionals might prefer the handheld editions of games even when they have the funds to play on a "bigger" console.