Idk about u guys but I dont buy a console until there is a healthy selection of games I really want and cant get on my current systems. Most people seem to agree that the main reason to own Nintendo consoles is to play Nintendo games so why would the majority of Nintendo fans buy Wii U when basically every major Nintendo franchise has yet to release?
Up to this point the only big hitting Nintendo franchise to appear on Wii U is 2D Mario and a few smaller ones like Pikmin 3 and Wind Waker HD (a niche series and a remake) so really there hasnt been much reason to own a Wii U yet even for hardcore Nintendo fans.
Next week has 3D Mario, February has Donkey Kong, Mario Kart in the Spring and Smash Bros is rumored for May so in the next 6 months the number of system selling Nintendo franchises will increase drastically and Zelda is possible for holiday 2014 and X, Bayonetta, Yarn Yoshi can help fill out the second half of 2014 as well.
The same goes for casual gamers as there hasnt been much incentive for them to upgrade from Wii/Kinect yet. At launch they had 2D Mario/Nintendo Land and Game & Wario in June. This holiday has Wii Party/Fit/Sports Club, Mario & Sonic Olympics, Mario 3D World and Just Dance/Skylanders are being bundled to help move those fans over. Next year has games DKC, Smash, Kart, Yoshi which appeal to both casuals and core Nintendo fans.
If this holiday and next year still dont see Nintendo fans and casuals buying a Wii U then its alright to call out people for not buying one but until there is a strong selection of games that appeal to those crowds there is no reason to buy a Wii U.