Galaxy 2 isn't a "necessary" part of the collection, but its omission is very strange, seeing how it will now be the only 3D Super Mario (besides 3D Land) not playable on the Switch. And I doubt that porting Galaxy 2 would take much work with Galaxy 1 already being ported over.

galaxy 1 is the more iconic of the duo
im probably gonna be called the next poochyena for saying this…
galaxy 1 is a 10 as where galaxy 2 is a 6.3