When we paid money for services rendered time and time again. Times change, coverage and offerings should grow with advancements. It's not very confusing.
Apparently it is confusing for you. Regardless of whether US telcos are decades behind (which I believe they are) when you pay for service, you are not paying for better future service, you are paying for the service you have already received. The motivation for a telco to provide better service is to get more costumers, NOT because they signed a contract with their costumer wherein they promise to use the fees to create a better product.
Your idea is nice, but its far from the reality of any business where you pay a monthly fee for a service. I can't off the top of my head think of an industry where this is the expectations. But I can think of dozens upon dozens of examples where what you pay for is what you get, and no more (see every one of my monthly bills).
I don't complain because my gym doesn't add new equipment fast enough. When I signed up for my gym I checked everything out, and made a business decision. I decided that what they were providing was worth the price, and if they provided more in the future, awesome.
If the same service suddenly costed more, OR if the same priced service suddenly lost functionality, I would understand the complaint. However neither of those scenarios applies to AT&T offering the Microcell.
...and this is exactly why they should get this device free. By providing it for free it ensures they get to have that customer which will far exceed the device cost.
The basis for your theory is that every costumer that they don't provide this free (yet expensive to provide) device to is a lost costumer. In my opinion this basis is extremely flawed. Costumers don't leave because a company provides a new service, and keeps the current service the exact same.
Cell companies should provide service most everywhere to meet the demands of customers, it's not hard to understand.
They should, and this device helps them do that. We both agree about this it seems, we just don't agree on whether the costumer should have to pay for better service, or if it is somehow an inherent right.
However what you are paying for is NOT "better future service" or "100% coverage", and any costumer who thinks that is a fool.
I've worked for T-Mobile and AT&T as a field tech and also as a NOC Tech watching over their main cellular infrastructure. The large telco companies, they just refuse to get with the times, innovate or simply do what's right for their customers and themselves. I'm rather amazed anything telco related works to any reliability really with what I've seen over the past 10 years.
As a person in a technical field with general understandings of communication infrastructure, I agree 100%. But just because some other country provides the people different color water on demand, with temperature control down to the half degree and for less money, doesn't mean I suddenly have the right to demand the same thing from my own water provider for free. At least IMHO.