On the Wii U, I could get behind such but not for the 3DS, Nintendo actually gets a lot of push thanks to Capcom's Monster Hunter series, along other RPGs, such as Sega/Atlus' Etrian franchise, random Mysterious Dungeon games and other ones. So they don't want to step on a valued 3rd party partner's toes in the bigger market.
The Wii U however could easily use some extra games, a co-op action RPG of some kind could easily be done using an existing popular IP like Zelda, Fire Emblem, Pokemon or even Xenoblade or it could be a revival of franchise such as Mysterious Murasame Castle or even brand new IP. They have options, its a matter of using them.