I have a feeling Nintendo are already pushing Wii U to its limit with BotW. You can only optimise so much for the Wii U. Then Nintendo should cut down the foliage, shadows and lower the resolution of the Wii U version. In the end you can't get parity with the Switch version when the Wii U is a lot weaker, especially with a docked Switch and devs having three times the memory to work with.
Do people get mad when a console game gets ported over to PC and performs 100x better? Better HW = Better performance. I understand the Wii U version is less than ideal, but it is what it is.
It's not a big fuck you, if you decided to buy it for the Wii U. There are plenty of videos showing the performance of the game for both versions. You paid 60 to play BotW, I paid 390 (not including additional accessories, like Pro controller for 70) to play BotW, even though I already have a Wii U. That's a lot of money for basically one game, but I wanted better performance and portability. I also don't want to buy any more games for a console that's not gonna be supported anymore. So, there are up-and downsides for both of us.