The first iPhone didn't have an app store and the idea was to just use websites and later install webapps. On that there is no control whatsoever, so no I don't think the original idea was to lock down the devices for business value.
The iPhone had to add an app store because there were some apps that users couldn't build on the web at the time. They since allowed apps, but those apps are restricted to a proper subset of the APIs that first party apps get.