Subjective, I suppose.
Let's not talk about what could have been, but what is. To me, the Wii U software represented more than just casuals and core gamers. Games like Rayman Origins, Lego City: Undercover, and even Nintendoland are attempts to cater to all audiences- Lego's open world, acrobatic and GTA-styled gameplay is a deeper attempt at gameplay. Rayman Origins is kiddy in appearance, but its mechanics and platforming cater to a more "core" audience. And Nintendoland is minigames featuring the "core" Nintendo titles. I think it's a smart introduction into the console race, and it's showing that the Wii U is, essentially, a grown-up Wii, with more mature games and a recognition of what made the Wii successful (motion controls, simplicity) while also tossing in more mature overtones, a social network, etc.