On Xbox 360, all Xbox Live Arcade games were required to have demos, but Microsoft dropped this policy for the Xbox One. A fan asked Microsoft's Larry "Major Nelson" Hryb recently why the company changed its thinking, and he responded by saying demos are up to developers to create.
"It is (and always has been) up to game developers to do demos for their own games," he said in the comments section of his blog. "[There will] be more demos for Xbox One as the platform goes forward." No timetable was provided.
On Xbox One, all games are grouped together. The digital marketplace does not make distinctions between indie titles or games on demand titles. "All games are treated equally," Xbox chief Marc Whitten told GameSpot in August.
In September, Whitten revealed that not all Xbox One games would have demos like Xbox Live Arcade titles had on Xbox 360. "That said, we are going to work on lots of ways to make it easy for you to find and try new games on the service," he said at the time.
In fact, just five of the 26 available Xbox One titles has a demo. These are FIFA 14, Zoo Tycoon, NBA Live 14, and Zumba Fitness World Party (in addition to a demo for the currently unreleased Kinect Sports Rivals). In addition, while not exactly "demos" per se, games like Killer Instinct (the "world's most generous demo," according to Microsoft) and Xbox Fitness are free-to-play.
If developers are indeed deciding to cut back on game demos, it could be to save money. Designer and games academic Jesse Schell said during the DICE 2013 Summit this year, citing data from the NPD Group, that releasing demos can cut game sales in half.