Image & Form announced the release date through their Instagram page today...
I just beat it on 3DS myself after having beaten it twice in early January when I discovered the game. I might be interested in triple dipping... Rumor has it they are working on allowing a discount for existing owners of the game on 3DS when they buy on Wii U.
Has anyone been holding out for a Wii U version? Little is known about it but I wonder if graphics will be at all rezzed up,... but then again the PC/MAC version looks nice and I'm sure is the graphical quality they needed for a Wii U version. I wonder what, if anything, the gamepad can bring to the game.
Still, with hopes of a SteamWorld Dig 2 and future titles from Image & Form on Nintendo platforms, I'm happy to see this coming into fruition.
I'll buy a game on any system if I want to play it. The thing is, there are hundreds of games released every month, so I don't have the time (or money) to get everything I want. Therefore I typically wait months and even years before getting a game.
Having beaten it twice on Steam (Mac) I can say I think you've got an incorrect assessment. It works just dandy. I don't understand why the handheld would require the simplistic game and not a console.