What other class of good is so tied down as phones? It's not going to come down to availability at carrier stores or nothing.
It's been tried how long to get traction with the OS through US carriers? And what has that gotten? Minimal and stagnant results. If the carriers have so many conditions on what a phone can and can not have to sell in their store they should build their own phones.
If Microsoft builds the phones pure to their vision, the carriers should have the option to take the phones
as they are. It is more than enough with the monkey business that US carriers engage in. "Yeah, we'll take that model so long as no one else in the US can have it". Then they shove it to the back of the store and ignore it. Or worse yet, "Yeah, we'll take that model. But not as you have it configured, it should be made less functional with the following hardware downgrades..." And then they still shove it in the back of the store and ignore it.
Look at these Bing Results for AT&T Lumia Promotion:
https://www.bing.com/videos/search?q=at&t+lumia+promotion&FORM=HDRSC3
And this Results page for AT&T Samsung Promotion:
https://www.bing.com/videos/search?q=at&t+samsung+promotion&FORM=HDRSC3
And AT&T iPhone Promotion:
https://www.bing.com/images/search?q=at&t+iPhone+promotion&FORM=HDRSC2
Which one looks least current? Which one looks least like the carrier is engaged with the product and happy to stock/sell it?
Continuing to present your product via partners that actively work against the OS will not get results. It's like trying to sell fresh healthy vegetables out of a pig trough filled with slops.
The carriers have Americans conditioned to follow their sales model and it does not have to be that way.
I'll say this, there is not a Microsoft within 3 hours of where I live and I'm more than happy to volunteer that Windows Phones be pulled from carrier stores if it means pandering to carrier idiocy. Some people will just have to sacrifice their convenience for the health and well being of the platform.
There are other brick and mortar retail outlets that can stock and sell phones. Personally I've gotten my last I don't know how many phones off the internet including my undiluted Lumia 1520.3. The last time I bought a phone out of a carrier store for myself was probably 2005. I've had a lot of phones since then.
Complaining that you won't get a phone unless it is in a carrier store is just playing into the stilted game the carriers have established in the US. Doing it their way has no benefit for the consumer. Americans need to disabuse themselves of the incorrect notion that somehow when a carrier provides you with a phone it saves you money and is also done out of some kindhearted and public service oriented motivation. When a shark sees you in the ocean and takes a bite out of your backside, that shark probably believes it is doing you a favor and that bite is owed him anyway.