It looks to me that it's probably either that the game was rushed, or they put a junior dev team on it. I can't imagine it's the Switch hardware given how much more powerful it is than the Wii. Add that Frontier was loaded with beautiful environmental effects and animations that seem to be missing in 5.
Rune Factory Frontier (Wii)
Rune Factory 5 (Switch)
I describe myself as a little dose of toxic masculinity.