Who exactly was Nintendo's primary target audience with the Wii U?

[Soundwave]

This is the first year Nintendo lineup for the Wii U ...

New Super Mario Bros. U
Nintendo Land
Sing Party
Ninja Gaiden 3 port
Game & Wario
LEGO City Undercover
The Wonderful 101
Pikmin 3
Wii Fit U
Wii Sports Club
Wii Party U
Super Mario 3D World
Zelda: Wind Waker HD
Mario & Sonic Olympic Games

That's 8 party/mini-game titles. 2 multi-player casual friendly Mario platformers. A Zelda remake. Two kinda mid-tier Nintendo core releases in Pikmin 3 and Wonderful 101. A kids licensed game in LEGO City. And one port of a "hardcore" PS3/360 game, Ninja Gaiden, which had mediocre reviews.

Anyone who can say with a straight face this is a product aimed at "hardcore" gamers when literally 2/3rds of the games are casual fare is out of their mind. A port of the shitty Ninja Gaiden 3 is the only thing expressly not for casuals or kids.

It was for casuals. The casuals just didn't come back, and there were signs they were already leaving later in the Wii's lifecycle.

They didn't support the Kinect either on XBox One.