In an interview with Joystiq, Monster Hunter 3 Ultimate producer Ryozo Tsujimoto has confirmed that the Wii U version of MH3U will not support off-screen play. Tsujimoto explained the reasoning behind such a move is that the game needs to maintain the two-screen experience available on both the 3DS and the Wii U:
We don’t have that feature within Monster Hunter 3 Ultimate – really, the way that we approach making the title for the Wii U was that we wanted to make the Wii U GamePad subscreen a compliment to the main screen. So instead of making the screens replaceable or being able to switch them, we really wanted to make sure that players are utilizing both real estate of the screens, in conjunction with each other.
The reasoning behind the move makes sense, so I’m not too upset that the game will require the TV at all times. Not to mention if you really want to sit on your couch and play the game, you could always just buy the 3DS copy of the game. Amazon is currently running a promotion where if you buy both the Wii U and 3DS versions, you get $20 off, so that makes this option that much more attractive.