The extra usability is a function of the carrier's network, not anything on Skype's end. And since many of us are already paying our carriers for data plans, why should Skype arbitrarily charge us a second time? I still don't get it.
> why should Skype arbitrarily charge us a second time?
1) because they can; 2) who's going to stop them (definitely not carries who gain on that agreement)
Now I'm just hoping someone comes out with a iChat/AIM/Jabber/GTalk-like P2P standard for voice (does this already exist?).