Makes complete sense!
In comparison to Astromech droids, practicality wise, its a work of genius:
-Unidirectional movement because of the ball shape instead of forward/backwards movement of Astromechs (and mouse droids, for that matter).
-The shape would also allow the droid to position itself utilizing spherical angles to provide sight sensors and receptor systems many options for fields of view.
-Gyroscopic stabilization systems incorporated into the shape make it extremely mobile and stable, impossible to suffer from being knocked over, making it even more self-sufficient than Astromechs.
-Such systems would also make the droid more evasive and capable of maneuvering over or through various types of terrain. Possibly buoyant.
-Small size makes it compact and easy to transport instead of bulky, trashcan-shaped units that take up valuable cargo space.
-Also on size, housing systems made to accommodate such a droid won't need to be as demanding for designers wanting to integrate it into spacecraft.
-It's probably going to be in a bunch of FIFA ads.
This, of course, is under the assumption that this new Soccer Ball Droid (SBD) was made with the same intention as Astromechs and that it is expected to fill the role of an Astromech in the new trilogy.
I'm excited about it already.