No. Madden NFL 12 on Wii does not require Wii MotionPlus. It is fully playable with a standard Wii Remote (+ Nunchuk).
However, Wii MotionPlus enhances the experience:
Without MotionPlus, these actions map to button presses (A for catch, stick for juke) or basic waggle detection. The game auto-detects the accessory.
Recommendation: If you have MotionPlus (built into Wii Remote Plus or attachment), use it. It makes the Wii version’s unique motion controls feel intentional rather than gimmicky.