Digging deeper. Very interesting. Lets get the definitions out of the way:
1. an ingenious or novel mechanical device
2. an important feature that is not immediately apparent
3. an ingenious and usually new scheme or angle
4. a trick or device used to attract business or attention <a marketing gimmick>
Source: http://www.merriam-webster.com/dictionary/gimmick
As for whether a "gimmick" is software or hardware is easily answered. It can be both. Super Mario 64 was just as much a gimmick as the Nintendo Wii is. Both are "an ingenious and usually new scheme or angle" on how the play of a video game is done.
Of course, this is not the real question. From:
It's a question of the ORIGIN of the innovation. Is it software driven? Or is it hardware driven? Do the games dictate the innovative hardware? Or does innovative hardware dictate the games?
This is the heart of the matter. Does the hardware sell the software? Does the software sell the hardware?
You will not find the answer looking only at today or the PS2 generation. You need to look further back at the Sega Dreamcast, Sega CD, Jaguar, and Neo Geo.
All of the aforementioned were gimmicky hardware who were the most powerful of their time. Yet, they were outlasted by the technologically inferior SNES and Sega Genesis.
Looking at the history, the games and where the developers see the games going drives the innovation. Thus forth, the software drives the innovation. Hardware is simply a means to the end of running the software for the mass market consumer to play the game.
No one buys hardware for hardware's sake. Hardware is bought solely to run software. Hardware is a means, never an end.
If you think hardware is an end in of itself, then you are surely still playing the Sega Dreamcast because it was years ahead of it's time...Wait, what new games are coming out for the Dreamcast?
