The US New Bike Market is largely divided between SPORTBIKERS and CRUISER RIDERS. All the other bikes on the market make up a tiny percentage compared to cruisers and sportbikes.
Then you've also got the
"BIGGER IS BETTER" idea that's really also a North American phenomenon. That's paired with stubbly numbnut idiots who only feel worthwhile if they can say
"MY BIKE IS MORE POWERFUL THAN YOUR BIKE".
In other words, why would manufacturers want to spend time sending bikes to the states where most people don't want them? (Sending them is not the only issue, they would also have to homologize the engines for US emission standards and create the parts/supply network)
You know, You, Me and a handful of other riders who like these midsize naked bikes just aren't worth the effort. You have to convince Mr. Cruiser Dude and Mr. Sportbike Vermillion X dude that there are plenty of other bikes out there and they are worth buying and riding. They've backed us all into a corner with a relatively narrow mindset - limiting our availability.
But you caqn't blame them, really. This is capitalism at its finest. It's the world we've all created for ourselves!

“People demand freedom of speech as a compensation for the freedom of thought which they seldom use.”
- Soren Kierkegaard (19th century Danish philosopher)