It can only be a matter of time. If you think about how the landline market has matured from just BT to everyone else, the MVNO market must evolve to cater for new demand. Whether joe bloggs wants data access now is irrelevant - in a couple of years (if not months away) logging on from your mobile will become second nature for most people. That is the way phones are starting to be sold now e.g. update your facebook profile etc.

There will come a time when a tariff is attractive, not for the amount of minutes and texts, but because of it's inclusive data.

If the latest tesco offer of all you can eat for £30 included data, would you move over? (subject to 3g coverage etc) I'd consider it.