I wrote 900p@30fps for a reason ;) The Wii U version runs at 720p, and the frame rate is a bigger problem (both versions aim for 30fps, but “dips” happen much more often on Wii U, from what I’ve read). In addition to that, loading times are much faster on Switch due to the switch to cartridges.
And if that’s not enough, there’s also the “fact” that many of us want to play other Switch games this year, so why wait?