People don't have any idea what a gimmick is....
>.>
A gimmick is a marketing term.
3D is the gimmick for the 3DS, because its provides the cornerstone for the marketing.
Waggle was the gimmick for the wii, because thats how it was marketed.
Bluray was a Very Big gimmick for the PS3.
And Graphics is a very big gimmick for both the PS3, and the 360.
People use the term gimmick in an attempt to make something look shallow, but really it doesn't really mean anything in the end, because its only the gimmicks that set the products apart.