The Conduit would feature MotionPlus, but it turns out that High Voltage has tried it, and decided to take it out of the game. Why, you ask? Well, High Voltage's VP and chief creative officer Eric Nofsinger tells 1UP that Nintendo provided them "with early hardware and good developer support," but when they put it into The Conduit, it "didn't really add anything for our primarily ranged combat."
Nofsinger also got a bit more technical, adding that High Voltage hoped MotionPlus "would allow for better off screen IR tracking." Instead, Nofsinger says the device "seems to lend itself more naturally for hand to hand combat" and that it "doesn't feel like an optimal fit for how we had designed our moment to moment gameplay." Well, that explains it.
Sure, we want as many features as we can get our hands on in a game, but if it doesn't improve on the experience and just feels tacked on for the sake of being a bullet point on the back of a box, it's not worth it. It looks like High Voltage agrees.