My instant reaction to this was “what’s the point?”. Speakers live at home, as do WiFi networks. However, with a bit of help from Jordan Golson, my opinion has reversed.
The current implementation requires both devices to be connected to WiFi networks. On the iOS device, this is okay. But, on speaker systems, entering WiFi passwords is a user experience nightmare. AirPlay Direct removes this requirement, eliminating the speaker from the setup process entirely, which is a direct improvement to users.
Moreover, it makes AirPlay much more appealing to mainstream consumer accessory manufacturers, who would no longer need to include complicated remotes or touch-screens in order to facilitate the connection experience to support AirPlay. They can just concentrate on making a great speaker (with WiFi antennae hidden inside).
AirPlay Direct is an important step in making audio AirPlay equipment as ubiquitous as iPod docks.