If they have no access to any other computing equipment (which is very likely with the global budget phone market), then this could well be a way into the web.

I'm not saying it's as good as a touchscreen, but it's better than WAP and it's better than nothing. For most of the world those may be the only choices they have with regard to web access.

On the data plans issue, that's nothing to do with hardware at all. I've had an unlimited mobile network data plan for a couple of years now, and my network operator doesn't care what hardware I use the SIM card with.