Skype has always been reluctant (slight euphemism there) to let third party software connect to its network.
Although this whole idea was kinda put on its head with the release of the SkypeKit library. Unfortunately its licence is specifically open-source incompatible so it can't be used in Pidgin (but it is used in Trillian) - so for now you're stuck with the other Skype plugin for Pidgin.
"We don't care. We don't have to. We're the Phone Company."