To me the term "commuter", as it applies to motor vehicles, has more to do with how a particular vehicle is used, as opposed to what it is designed to be based on unique characteristics specific to that vehicle. A guy drives a Porsche 911 to work, day in and day out, so he is commuting with it, but it is still what it was inherently designed to be... a sports car. Same holds true for a guy who commutes in a Chevrolet pick up truck. In my mind, the CBR250R is no more or less a commuter than a Dual Sport, or a Cruiser, or a GSXR, or a Gold Wing. "Commuter" is more of a term of usage, not necessarily a strict design parameter, although I think Scooters may be more suited to commuting than to any other type of use.
To me, what categorizes the CBR250R as a Sport Bike, is that it shares a similar frame geometry with other Sport Bikes, regardless of engine displacement. The Honda XR650L shares similar frame geometry with the new CRF250L, and that is what defines them as Dual Sports. Cruisers have their own unique frame design. And so on...
The design of the frame, more than any other element, is what defines the "category" a particular motorcycle falls into, not how the bike is being used at a given moment. Anyway, that's my take on it.
To me, what categorizes the CBR250R as a Sport Bike, is that it shares a similar frame geometry with other Sport Bikes, regardless of engine displacement. The Honda XR650L shares similar frame geometry with the new CRF250L, and that is what defines them as Dual Sports. Cruisers have their own unique frame design. And so on...
The design of the frame, more than any other element, is what defines the "category" a particular motorcycle falls into, not how the bike is being used at a given moment. Anyway, that's my take on it.