Unfortunately the moped laws just aren't sufficient. The 2mph difference between a 28mph class 3 ebike and 30mph moped means anything that legally counts as a moped doesn't make any sense in the market. (Though critically the class 3 needs pedal assist for it's highest 8mph)
I disagree that these people wouldn't ride a motorbike, I'd argue that they are riding motorbikes, and while certainly some of them are happy to be hooligans who don't register their bikes, many more would happily register and pay insurance for these lower powered bikes if they were manufactured as motorcycles. As for gear, most of them seem to already be wearing motorcycle helmets and gloves, but whether they're ATGATT or closer to a squid riding in shorts and a t-shirt has no bearing on the bikes themselves or their ability to be registered.
Edit:
So it looks like more recently HUCK has added info on the moto version of their bike.
Info here. Judging by the pictures of the moped version it looks like they haven't actually produced the Stinger X yet.
They only offer the bigger battery in their motorcycle version, but that expense gives you a 60mph top speed, 3.6kwh nominal battery for $5500 with tax included. Taxes of course vary by state but in CA that would make the pre-tax price to be $5116.
Which is to say yes, you can build an electric motorcycle in this price range with desirable specs. There are a lot of younger riders and college students for example that would absolutely start with something like this for their first bike, that would not be able to afford the next step up to a Zero FXS for $4000 more. But they've never had registerable options before.
The other thing to consider is tax incentives. Fed incentives are about to expire but potentially these bikes being registered as motorcycles could lead them to eligibility for california's KWH based tax rebates. Wouldn't have an astronomical effect on price point, but it would certainly help.