Every current standard was once a potential gimmick.
Those motion control gimmicks by the way, are becoming a standard. More and more devices have gyroscopic sensors, and applications and games that make use of them as simply another tool in the kit that gets used in due time and place.
What's a gimmick in the most pejorative sense of the word? Red flame decals on the side of a sports car to make it go faster. Also, that giant Pikachu N64. Yep, that was a gimmick.
But "gimmick" gets thrown around way too often and easily by folks who just don't like something and wish it would go away so they don't have to see it anymore.
Straight from Wikipedia. If you have a better source or a better official defintion, they go ahead:
In marketing language, a gimmick is a unique or quirky special feature that makes something "stand out" from its contemporaries. However, the special feature is typically thought to be of little relevance or use. Thus, a gimmick is a special feature for the sake of having a special feature. It began, however, as a slang term for something that a con artist or magician had his assistant manipulate to make appearances different from reality. Such things as the manipulating of a gaming wheel led to the idea of a "gimmick" being used. Musicians often use gimmicks such as Slash's top hat, Angus Young's schoolboy uniform and Deadmau5's mouse helmet.[1]
In marketing, product gimmicks are sometimes considered mere novelties, and not really that relevant to the product's functioning, sometimes even earning negative connotations. However, some seemingly trivial gimmicks of the past have evolved into useful, permanent features. According to the OED, the word is first attested in 1926, defined in the Wise-Crack Dictionary by Main and Grant as "a device used for making a fair game crooked".
Do you understand it now? You cannot be more wrong by calling the N64 Analog Stick and Motion Controls - both revolutionary input devices - a "gimmick". It cannot be that hard to understand it, can it?
The Wii U Gamepad has far too much functionality (motion sensor, tuoch-screen, wireless lag free technology, camera, speaker, mic, NFC) to call it a gimmick.