1. No one, not even Nintendo, had any idea that Wii Sports, or motion controls, were going to be the big hit they were. Any more than they had any way of knowing Nintendo Land would subsequently NOT be a big hit. Wii Sports and the Wiimote were untested. And Excite Truck is not exactly a system selling title. So Wii launch "needed" Zelda, because it had nothing else proven to launch with. Many people got on board after word of mouth about Wii Sports spread like wildfire. But a LOT of early Wii adopters got their system FOR Zelda.

Wii U will very doubtfully be in that position. If nothing else, it'll have a new 3D Mario out of the gate, and Mario games have traditionally always sold more than Zelda games.

2. The notion of loading up NX's launch with big titles is honestly misleading. It may create fan excitement of the very IDEA of, say, NX getting Mario, Zelda and (let's just pretend) Metroid all at launch. But in actual execution, most people don't have the money to buy a brand new system AND several games all at once. And launching all those big franchises at once, even Mario and Zelda together, may not be smart in and of itself. There's a reason, strategically, that they tend to spread those releases out: so that people have the big franchises to look forward to down the road, and so each big game release has it's own "window" and spotlight.

Throwing a bunch of games at launch doesn't guarantee success.