You know, looking back (even though I thought it at the time), Apple made such a pivotal decision with the iPhone to make it contract with unlimited data plan only.
At that time, it was obvious to me that they wanted to make this the kind of device that people are experiencing now - a device that you actually use a LOT of the features. You know, as opposed to other phones that have the same feature set, but for some reason, be it UI, user experience, or whatever, but they don't get the same use.
By making it online ALL the time (and pretty much requisite for the typical iPhone user), people DID use it. And it paid off big time for Apple, as people find new ways for it to help them. If they offered a range of data plans to suit all walks of people, you'd simply get the entire range of opinions. "Oh, it's not that great." "It's just like any other phone." "It hasn't changed my life.". By fixing it at a premium, unlimited, always connected use, you have the same repeated experience for a lot of people - and that word spreads.