TL;DR: Nintendo has had an extra year so of course they have more games, give Sony and MS time and Nintendo took a while as well.
Many times a day I see on here and the interent post about how the Wii U has many more exclusives than the PS4 and X1 and that they are an embarrassment in comparison etc.
I know the sales difference can make people forget but Nintendo have had a year longer to pump out first party software for it. If you were to take away the past year from the Wii U and put it on point with Sony and Microsoft's machines you'd have to subtract:
Mario Kart 8
Super Smash Bro's
Mario Party 10
(I'm not sure what else I'm forgetting)
All of these are big hitters Nintendo didn't have last year we all know how SLOW they were at making games at the beginning but we all knew they would deliver because of past gens. So why not the same for at least even Sony, who's first party line up on PS3 had quality, quantity and diversity.
PS4 and PC gaming
AMD Ryzen 9 3900x
Zotac Nvidia RTX 2070 Super
32GB DDR4 Corsair Vengence Ram 3200 mhz
1TB Samsung Qvo SSD
Corsair Spec-Delta Case
Asus ROG B450-F Motherboard