From a business perspective it makes a ton of sense. The Wii U's failure meant a very small install base to work with, and while its biggest games had insane attach rates, they could have reached a much larger audience on a more successful system. People who passed on the Wii U but who are getting a Switch will likely be interested in picking up notable games that, despite being re-releases, are new to them.
And as a Wii U owner myself, I'm interested in double-dipping on some titles just for the portability aspect and the performance boost. Also, there was a couple of games I never got around to picking up.