I believe these games are the only retail one available on the Wii U that do more than provide a simple map screen or offline play on the GamePad.* If Nintendo wishes to keep the GamePad as the primary Wii U controller (and it looks like they do) why not bundle these game free for a limited amount of time? Let gamers buy a Wii U and have a free digital copy of ZombiU and Nintendo Land which they can try out for 30 days before the game stops working.** These games will be free along with the free Mario and Zelda game bundle.
These two games are probably the best way to show how the GamePad is relevant and fun for gaming.
Or even better, make these free games still free after the 30 day expired, but for every 30 minutes, the consumer will have to watch 2 minutes of advertisement before playing again. If they buy the game, the advertisements will stop.
* I do not own a Wii U nor have I played many Wii U games. This statement is an educated guess backed by my experience of Wii U games from the internet.
**The save file will still be working in case the cosumer wishes to buy it and continue from where they left off.