I mean, in the US, they are releasing it as one game anyway. Legacy Collection 1 & 2 come together as one game if you buy a US physical copy. Unless you buy it on the switch, in which case for whatever reason the physical copy is only Legacy Collection 1, and there's a download code for Legacy Collection 2. (though it still technically is all bundled as a single game purchase)
I dont get why they didnt just rebrand it as Mega Man X Legacy Collection and sell it as one game if they are gonna bundle it all as one package anyway. Why go through the rigamarole of selling "Mega Man X Legacy Collection 1 & Mega Man X Legacy Collection 2" as a single box, and not cut out the middle man of that awkward title, when the standalone games will never be released separately like they were in Japan?
This is almost as awkward as that DS greatest hits cover where it's a DS box within a DS box