Wii U was obviously designed for casuals. First of all re-using the Wii brand (synonymous with casual gaming) and almost half of Nintendo's releases in the first year were casual centric mini-game collections on top of the big launch title being a New Super Mario Bros. game. Nintendo Land, NSMBU, Sing Party, Game & Wario, Mario & Sonic Olympics, Wii Party U, Wii Fit U, and part of Wii Sports Club were all released in the Wii U's first year.
The only other games Nintendo published were Mario 3D World (a 3D Mario tailored more to NSMB casuals), Wonderful 101, LEGO City, Pikmin 3, Zelda: WWHD, and Ninja Gaiden 3. Arguably the only game there expressly aimed at hardcore players is Ninja Gaiden 3 which a 6-month late port of a crappy PS3/360 game. The system is clearly aimed at the casual market + the kids/family demo.
The new controller was also made for casuals too IMO, a giant touchscreen is for the casual demo, they just surrounded it with traditional controls as an olive branch to having a more balanced user base.
Saying the Wii U wasn't initially targeted at casuals is like saying a Twilight movie isn't aimed at the teenage girl market just because it has one or two action scenes in it.
