Handheld market outside of Japan is more centered towards kids, so graphics don't matter as much as low price point + kid-friendly franchises.
Console market is a different beast, the 14-35 year old males who drive the market don't want handhelds, they want a home console to play on the big screen with high end visuals.
Wii U is not what they want after 6-7 years of the 360/PS3.
Casuals aren't interested because there's no "hook" to the system like the Wiimote was. People who want Just Dance can play that on their Wii for $30.
Nintendo's basically stuck relying on their core fanbase. And the problem with that even is that a lot of Nintendo fans are not accustomed to paying high prices for hardware, so a lot of them are holding off on the Wii U for $300-$350, which probably explains the abyssmal sales all around even with Super Mario + Nintendo Land.
The 3DS is also selling no where near the types of numbers the DS was in its prime in the West, Japan is really carrying the platform often selling as much Europe + North America combined week to week.
