The credit is useful when she's not on skype and I can use a few cents (if that) to dial her landline from the other side of the world and say "Hey, turn your computer on!". It's true this is no longer that special - I get a few hours international calls for free with my mobile plan these days so I don't need-need skype for it.

I imagine the reason they want to move to a subscription model is that there are too many people like me - $10 credit lasts a few years and probably represents a liability on their books as well as a customer they aren't getting any more money from for some time.