Wii U had one huge disadvantage over N64, GameCube, Wii, and Switch. It was their first HD console. Plus, they were still pushing 3ds games, so why would there be sequels to 3ds games on Wii U when they still wanted to sell 3ds? They wouldn't be unified until Switch. Aside from that, most people didn't know it was a new console.
Wii had basically no power jump over GameCube, so their software teams were already used to programming on that level. Same as Switch over Wii U. I can not really see any difference in mk8 delux over 8, or tropical freeze switch vs u, or any other re release. By the time Switch came out, they were used to U's capabilities. Wii U they were simply completely unprepared for and had a terrible name confusing the market.