The US is a nation of muscle cars an pickups
No market, no interest (the minority interest does not produce a successful business).
An easy parallel can be made to the US space program. No public interest, no 'dough flow'.
Other countries 'grew up' on a bicycle so they, as a culture, have that peice in them, we don't have it so our major resources sideline and clap for marketing monsters like HD, but really have no vested interest in a 'Powersport'.
Buell spent years asking HD to develop a motor. No dice.
Roehr tried to slide in the shallow end by using a Vtwin (strong parallels, but waaaaaaay less competition to go against)
Eccose, I feel, went boutique like Confederate. Performance, but not really a 'racing' design.
Even when we have the second coming of the Savior Britten
, I believe support will not come from the States.
These are all just my thoughts.