Since Starfox 64 they chilled the 3D effect out heaps. Starfox 64 on full 3D is about the same as Pilotwings on half.
On earlier games like Pilotwings/MonkeyBall the 3D was way too intense. Even Ocarina of Time was a little bit harsh on full 3D setting.
Also I read that they used a different 3D technique on Super Mario 3D Land. That's why there are 2 different 3D effects you can use. The default setting is the new method where Mario is the centre point and the 3D effect is all around him. The second setting Mario is part of the 3D like in Ocarina of Time.
They are just perfecting the 3D effect. It's very hard to feel sick playing Mario Kart/Mario Land on full 3D. But try playing PilotWings on full 3D for a few minutes and you'll feel like shit.







