“Usage-based bandwidth pricing is inevitable. Try getting your electric or water utilities to quote you a rate for “unlimited” use of their product.”
Electric and water are poor comparisons. A better comparison is cable TV or satellite TV. Just like 3G and 4G, the network is there whether you are using it or not and it costs the carrier nothing when you have it tuned in 24/7 for a fixed cost. Cable modem broadband internet is also unlimited for a fixed cost, and so is DSL. To have metered usage simply makes 3G and 4G uncompetitive for home use. Especially considering that it takes much less installation, equipment, and maintenance costs per given metro area to operate a 3G or 4G network than it does to maintain a cable plant covering the same metro area.
By contrast, if every household in a neighborhood turned on all their water taps at once the water pressure would plummet. So too, cellular towers have shared bandwidth (as do their backhaul links) so that the more people draw from them the less there is on a per-user basis. It's easy to provide "unlimited" data when (almost) nobody is using it. However the demand for mobile data is skyrocketing (thanks mainly to the iPhone and iPad) and the current situation is unsustainable.
Cable and DSL net access have the same issue, however because the infrastructure is denser and cheaper, you just don't notice. If it costs a mobile provider a dollar to provide a gigabyte of data that same gigabyte of data can be provided for a penny by the wired infrastructure. The actual numbers aren't important and change rapidly as technology evolves, but wireless data will always cost more than wired data so it makes sense that metering would appear there first.