Data plans were the disruption that made the iPhone more than "a faster horse." They allowed the iPhone's architecture to be feasible and the idea of the app store to be viable. Yes, touch screens are an improvement over pens, but the change that sunk RIM was logistical.
This is how it played out in Australia too. Pre-iPhone data was expensive. My pre-iphone "smart" phones were hobbled by a lack of data which the iphone didn't suffer from.
The iPhone (mandated) plan from AT&T was $20/mo for data, including 200 texts.
Even if I didn't prefer the iPhone, that cost differential was a no-brainer to me.