Oooo, so negative...
I would say it's a very good example of a game that has platforming elements which works in a first-person view.
But you're right, it doesn't lend itself to accuracy thanks to not being able to see your feet too easily.
Having said that, the rev controller might change all that. Imagine Metroid Prime controls (Control stick moves Mario), but you use the wand to move your view. That way if there was a Goomba in the distance, you would tilt forward on the Control stick to approach it. When you're near enough, you would press A on the wand to jump, then while in the air, you would point the wand downwards to see what was below you (or around you if you wanted), then use the Control stick to make fine adjustments so that the Goomba is in the centre of your view i.e. directly below you.
I'm sure the dev teams will have presented this and many other control schemes before deciding on the direction the game will take.