Well, it's intended as more of a starting point. Both Seamless and Groupon had to start in one city before branching out- it makes sense. If you tried to scale out to every city simultaneously it would fall flat on it's face.

As for reaching target audience, well, the NYC-centricity of it is an advantage when it comes to advertising. If Taxonomy was an actual backed business (right now it's little side project idea) it could even advertise on and in NYC yellow cabs some day. Expensive, but the target audience is looking directly at them.