Wireless is not a panacea even with spread spectrum. You still have a finite amount of radio spectrum you have to share with everybody within range. The amount of bandwidth you can serve to each customer with a fiber-terminating central office every square mile is limited in practice by the cost of installing fiber. The amount of bandwidth you can serve to each customer with a WISP every square mile is limited in practice by the laws of physics -- the only way to get more is to build a higher density of wireless base stations, and in higher population density areas the cost of that is on the same order as installing fiber to the customer premises. Moreover, the cost effectiveness of using wireless for the last mile goes down as the demand for bandwidth per customer increases over time, because you have to increase the density of wireless base stations and run new cable to each of them in order to expand capacity rather than only replacing the terminating equipment at both ends of an existing cable.

Wireless is a great solution to providing high bandwidth services in rural areas where the cost of laying new cable is prohibitive. It's not a solution for cities.

It's true that there is a rural/urban breakover point; I'd contend that is at far greater densities than most people think, especially if we made use of the entire spectrum rather than the drips and drabs meted out so far by the FCC. The portion of the population getting shafted right now, all the "rural" (and most suburban, and urban in Texas-style "sprawling" cities) folks, is definitely a majority. "Laws of physics" arguments aren't convincing at this point, since engineers have had their hands tied by FCC regs. Let a big market for this type of radio tech exist for a decade, and then we'll see what can be done.

You can't use the entire spectrum without addressing the sunk costs problem. All the existing users of the spectrum would have to throw out their equipment and replace it with spread spectrum equipment. Nobody wants to do that, especially when the benefit of them doing it goes primarily to third parties. You want to talk about phasing it out in favor of spread spectrum, fine, but that's going to take years or decades. What do we do in the meantime?

The next piece of trouble is, if you really want high power unlicensed spectrum, what do you do about contention? What happens when scientists start setting up transmitters to continuously send 50Tbps of scientific data from remote monitoring stations to the regional university's data center? Or people set up a distributed mesh network of Tor nodes? Or someone decides to operate a wireless "cable TV" franchise and starts transmitting 50,000 streams of 4K HD?

Don't get me wrong, I think you have the right idea -- spread spectrum is the way to go for wireless and there is room for a lot of innovation there if the FCC would get out of the way. Especially in the way of short and medium range mesh networks. It just isn't a replacement for fiber to the premises.