The US is full of large, leaky, poorly insulated houses designed without any mind paid to thermal performance. Until that changes, ductless simply doesn't work for many people.
I think ductless will come on its own as US houses improve.
Not just the US.. A friend of a friend moved to the UK and built a house the way we do in northern Europe. Her neighbors pitied her in the winter because the roof of her house was covered in snow...
I think ductless will come on its own as US houses improve.