It's just money. And in some cases, like this one, they seem unreasonably greedy.
There's a DMC 1-3 HD collection on PS3/360. Porting it over to Switch should not be difficult to the point where it warrants splitting them up into individual games again.
I get them being greedy and wanting an exploitative cash grab, that's par for the AAA publisher course. What pisses me off is that they refuse to bring anything to Switch that's not ancient leftovers from previous gen machines despite it proving time and again it can handle modern games and selling on par with PS4. (Or significantly better in Japan)
Bet with Liquidlaser: I say PS5 and Xbox Series will sell more than 56 million combined by the end of 2023.