Jonathan Morin, outspoken creative director on the game, explains simply:
Doing Demos take time, the focus is on the game. You will see more footage before release.
This isn’t the first thing that’s been seemingly sacrificed as Ubisoft focuses intently on the game: Watch_Dogs was originally planned to launch last November, alongside the next-gen consoles. However, just a month before release, it was delayed indefinitely, to give the developers more time.