Alright, so there is no "unlimited" data plan. You are right. What I meant to say is that we are assuming a reasonable data plan for users of high end devices.
Personally, I'd say your comments have much more in common with the '640k' arguement, because mobile technology and bandwidth are moving fast... and we are attempting to build something to last more than a few years.
At least with our personal mobile use, we don't worry too much about bandwidth, just load speed.
And yes, we have no support for IE and because Microsoft has yet to respond to our requests for aid, the ball is in their court.