1. Do you have *any* idea of the costs of installing and operating even a single cell site? It isn't easy or inexpensive to just "expand the network", or everyone would do it. Also, there are a limited number of radio frequencies to be used, and in high density areas, the spectrum is becoming very crowded. This is where the problems are, and this is where the cell providers need to find a way to free up bandwidth. The only way to do that is to discourage people from using it, and the only way to do that is to make them pay for it if they really need it.
2. Why should they expand their available data time, when they aren't making anything on it as is, and demand is growing rapidly with new, high-bandwidth apps? This is the same problem that even land-based networks are running into: in order to afford the expanding bandwidth requirements, they need to cover costs. That means finding a way to bill more, and the only way to do that is limiting access and charging for the excess. So, if grandma is just getting e-mail, she is charged little, but if Johnny is playing WOW, Skyping (or Facetiming), watching a Netflix movie, etc, he pays more. That's fair, isn't it?
...and 3. Like Apple really wants in on the mess that is Cellular! And would we *really* want Apple to have control over the network? I bet Skype, Hulu, Vudu, Netflix, and the Amazon store would be really, *really* slow on that network! Net Neutrality would not apply (as it doesn't now to mobile networks), and, even more importantly, it would be a private network with public choices available. Therefore, they could do whatever they want, and there would be no legal protections.
I know it's frustrating, but there's lots of issues at work here. Don't be surprised to see the other carriers move this way also, after the marketing potential is all used up...