I agree that the dork factor is working against the Segway, but I don't think it's the dominant factor in it's failure. If Segways were significantly better solutions to the problem of transportation in dense areas, ordinary people would have started to use them and the dork factor would have faded away.

In my view the biggest reason for the Segway's failure is that it's a product designed for an infrastructure that doesn't exist. Kamen and his team envisioned cities without cars when they were designing the Segway. Unfortunately all that's available are crowded sidewalks, making the Segway the most expensive way to move along at walking pace.