I suppose it is also a skill to make it seem fashionable and desirable, in the way that Apple did. Compare that to PocketPC and Palm Pilots etc. that came before the iPhone, and remember that you wouldn't see a teenager using one.
I suppose it also helps that mobile phones have become widely acceptable. I remember when it was rare to see someone with one (can't even imagine how bad the coverage was with so few masts around), and people would label them as "posers" for having one or using it in public. Perhaps the earlier Windows devices (which were very capable, and allowed apps to be installed, albeit not from a central repository like the App Store) were just too early in the market, and by the time people accepted them they wanted something different and new. Android and iPhone rode this wave.