The issue of providers and how the masses don't care are separate issues. It's not a cost thing... Sort of.
Providers complain about how much it costs to maintain and improve their infrastructure to further validate what they can charge and thus add to their coffers. With no regulation this will never change. It's a very capitalistic structure and if you could get more money for the services you provide to your employer, clients etc you would as well.

Now people like me and prob most of you don't really care about that. We want the best and will begrudgingly pay for it. Them making it cheaper won't make a substantial change in how many people use it.
I point to the recent Netflix fiasco to prove this point. Netflix recently bumped prices in the US by 60%. That was what for most users? $5-$20? Not alot of money. Still pretty decent value.
In the next 3 days Netflix saw 800,000 canceled subscriptions over the cost of a single blueray.
It's not about quality for the masses. It's not even about convenience. It looks to be more about entitlement and value.
From our point of view here in Canada ( were we pay more than the US for things like bandwidth and cell service) the average American seems to feel they should not have to pay over cost for anything. It's weird, a society based on capitalism that's choked at how much the true capitalists make.
Now if true HD streaming was free then we would see a greater demand for it. But since it's costs more we won't. How much more for true HD the average person is willing to pay is unknown. We (people like us on these sites) will gladly pay for it. Alot of us are waiting for the next great innovation and will toss our HTPCs and AVRs away to make room for it when it comes. Do I get an 'Amen'! We can say "sure the average person would pay $5/month more for 25mbps!" But we see value in it. If there's no perceived value then would you spend that $5 for anything more than bragging rights? Where are you downloading from to need that?
Unless its free or preferably cheaper than the current option the average American won't. Not because it's better. Not because it's the new standard. But because they feel they are entitled to having it for free and won't support a company that made billions last year that is charging for it and because they see no value in it.
It boils down to value. Unless a person sees value in it they won't pay a dime more for it. If there is no value then it should be free or cheaper. Torrents are a great example. Quality sucks even when it's not a cam yet look at how many people dl them? I do, but if I enjoy the movie I'll grab the blueray as soon as it is released. If I don't like the movie it's deleted never to be seen again. My wife doesn't understand that as she see's no value in quality. As long as its not blurry or garbled (basically as long as its 480p) it's good enough and thus no extra money should be spent on it. But I lover her cause she is happy letting me spend to get better. 8D
So until its free we won't see it in common usage.
In my opinion anyways. No insults intended just say'in what I'm seeing.