Oh, and axe those mop-awful characters
Coming from mop-it-up. Sorry found that funny (don't know why!).
I use "mop" in the place of "god". Nobody can be offended by such use of the almighty... cleaning tool.
Anyways, as for Wii Motion Plus: imagine the controller monstrosity of the Wiimote, Wii Motion Plus, and Nunchuk. That's an $80 piece of equipment that you wave around recklessly. Now, the Wii comes with a Wiimote and a Nunchuk, but if you want four complete controllers for games then you'll need to spend an additional $260. That's more than the price of the system. Nintendo passes off the Wii as an affordable system but then they tack on accessories like the Wii Motion Plus, which add hidden costs. $60 for a Wiimote and a Nunchuk is already a bit pricey, adding another $20 is ridiculous.
Nunchuk is a little different. You get one with your system. It existed when the system first launched, many people already have more than one, lots of games use it so it's something which is worth having. The game which Wii Motion Plus comes with may be something which lots of people are likely to buy, but you still get just one. People with no interest in that game will have to purchase the accessory (up to four of them!) separately if they want to play any game which requires it, and by the looks of it, not many will. Wiimote + Nunchuk is expensive enough, adding more to that is just going to make things worse.
Wii Motion Plus seems like one of those things which should either:
1. Have been included in the Wiimote in the first place, or
2. Have been held off for a few years when the successor to Wii is released.