Coming from Nintendo's FAQ...
All Wii U games purchased on the Nintendo eShop are automatically registered to your Club Nintendo account. See the eligible products list to see what games are available for Coins. Note: Due to certain system constraints, Club Nintendo accounts cannot be linked to the Wii Shop on the Wii U. Games downloaded through the Wii Shop on the Wii U (in Wii mode) do not qualify for surveys or Coins.
I'm not too sure how many people will be upset by this, but it's still sad to see. I wonder what the technical hurdles were that Nintendo just couldn't be bothered to tackle.