While I've only played the Testfire this past weekend, I never turned them off. I've always played with motion steering in Mario Kart Wii and Mario Kart 8 (but not Mario Kart 7 as I always play that in 3D), and I have the Shake Smash turned on by default in Super Smash Bros. Brawl. (Yes, I play exclusively with the Nunchuk scheme, though I use the Wii U GamePad in Super Smash Bros. for Wii U.)
Motion controls come pretty naturally for me. I noticed people tend to not really understand them much, considering the enormous trouble people have with Fluzzard in Super Mario Galaxy 2. When I see people try to use the Wii Wheel for the Mario Kart games, I see them swinging the Wii Wheel left and right in a wide arc--not as a steering wheel or handlebars, but something closer to a ship's wheel. I never understood why people keep doing that, since there's no logic there, except perhaps as a passive-aggressive means of giving them traditional controls.
Should I actually get the full game, I will also play using motion controls exclusively. Over time, it's become my "natural." I'd imagine the way some gamers struggle with motion controls, I now struggle with traditional controls.