Wireless Internet access does not have to be slow, but it often is. I'm at the beach this week, and the access point is about thirty feet away, right at the edge of the property, but the speed of the paid service ($28/week, much higher than in hotels and other venues) is abysmal.
Wireless is often oversold by providers, who don't provision adequate backhaul and/or try to cram too many users on each access point.
Design Nine just completed a preliminary design for a large mixed rural/city region, with both fiber and wireless service as part of the network. As usual, the cost of well-engineered wireless access points in rural areas on a per subscriber basis (with sensible subscription rates/access point, not inflated rates) gets very close to the cost of taking fiber to the same subscribers.
And the advantage of fiber, aside from much higher performance, is the ability of fiber, in an open service network architecture, to deliver not just Internet access, but a whole variety of services (hundreds) from dozens of providers. The triple play broadband model is broken financially, and nothing is going to fix it. The solution is to move to a new business model, the Layer 3 open services approach, that truly unleashes competition and innovation.