not sure why
@Hardy is hellbend on defending the Wii U. the reason it didn't work is because that console had no appeal.
1st most of the wii users didn't upgrade for a Wii U, if you look at the wii games that sold the most beside couple of mario games, the majority of games sold by the wii are :wii sports (most sold game on wii by far, 87millions), wii sport resort, wii play, wii fit, wii fit plus and such. That should tell you about what kind of audience bought the wii and what appealed them with the wii. Yeah they have wii sport on the Wii U but why would they buy another hardward for a game that is already basically the same as what they already have and they're surely already bored of those games.On the other side PS3 users upgraded to the PS4 and Xbox 360 users to the Xb1
2nd compared to his competitor Wii U is just meh. while sony was preparing the PS4(2013) and microsoft the xbox one(2013), nintendo launched the Wii U(2012). For gamers that's a joke, what will you take between the PS4,XB1 and the Wii U? Only now with the Switch that they have a hardward that is comparable to the PS4 and the XB1, that show how far behind Nintendo was, that console didn't appeal to gamers. Exclus turn over to exclus, what console doesnt have exclus? they gave what seemed like a small upgrade to the wii while people were expecting a new gen.
3rd you mention that many of the Switch exclus are Wii U port. Once again that's because nobody bought the Wii U so they're porting the best games. And that's why games like zelda and mario kart are selling like candies after being ported to the switch and still sold at full price. People wouldn't buy those games on the switch at full price if they already had them on the Wii U.
4th you're right, the marketing was poor. but once again it didnt matter gamers were aware of the Wii U but it seriously can't be compared to the PS4 or the XB1 so it was brushed aside.