The Kinect was not designed to be a motion sensing device that is inherently and only part of the Xbox 360, if it were, it would have been built in. It is not. It is a motion sensing device that you can connect to something with the right connector, with Microsoft hoping that would be the Xbox 360. And if you know anything about people, you know we like to play with things, especially things we like.
“Anytime there is engagement and excitement around our technology, we see that as a good thing,” said Craig Davidson, senior director for Xbox Live at Microsoft. “It’s naïve to think that any new technology that comes out won’t have a group that tinkers with it.”
Except of course Microsoft, or the people at it, were extremely naïve, because earlier...
A [Microsoft] representative said that it did not “condone the modification of its products” and that it would “work closely with law enforcement and product safety groups to keep Kinect tamper-resistant.”
Microsoft's model has typically been one of control. Control over Windows, control over the Xbox, control over Microsoft Office, and so on. It was Sony that made it easy to load Linux onto their PS3, not Microsoft and its Xbox 360, although Sony later took away this capability (I am not sure of the politics behind that one, it may be interesting). Note that hackers have adapted Linux for both platforms regardless.
But we've seen so many instances where people do like to play with things (it's a part of who we are). For instance, Bethesda's line of games, such as Oblivion, which is available for both the Xbox 360 and Windows. There are no mods for games or anything on the Xbox, it's not part of the business model. (Mods, made by players, opposed to patches and DLC, by the company.) On the PC, however, there is a thriving mod scene (which I have written about). Bethesda supports the modders, gives them forum space, and interviews them (here is one example, and you can check out their posts tagged "modding"). The people at Bethesda know we like to play games and play with games, and we will do so whether they want us to or not. Mods can, and do, fix bugs, add new maps, zones, characters, quests, and everything: for the game producer, your customers can be developers who make the game better, for free. It's not just win-win, it's win-win-win (producer, modder, players).
Here's a recent Ten Best Oblivion Mods list from PC Gamer. Keep in mind Oblivion is over four years old already. In part because it's a great game, but in part because of the mod scene, people are still playing it.
I'm not sure, definitely, how old the modding scene is: the Internet itself is essentially a giant mod, so, 40 years. It depends on your definition. The Flight Sim mod scene is pretty old, dating back to at least 1990. That's 20 years (and Flight Sim is now, or was for a long time, a Microsoft product!). One would think that everyone would have noticed this long-standing given (I resist the word "trend" there, this is a not a trend, it is a constant).