There's a selfish part of me that wants the last few Wii U exclusives to remain exclusive, just to give that system some reason to have existed. But aside from X the entire Xenoblade series is available for the Switch so why not give people the option to enjoy it all. Due to the obscurity of the series before the Switch (late Gamestop exclusive Wii game, Wii U exclusive, 3DS port that requires the NEW 3DS) I wouldn't be surprised if the majority of fans have only played the series on the Switch so might as well make everything available to them.