...wondering why this isn't easier...
Knoppix doesn't include or facilitate inclusion of Skype as it might.
In researching why this should be, I have learned that there are both
licensing and potential security issues that cause this to be so.

Skype terms of use:
http://www.skype.com/en/legal/tou/
See especially the licensing section.

Skype security considerations:
http://security.stackexchange.com/questions/16407/skype-security-linux\
See especially Ninefingers' comments.

Without belaboring onerous licensing and potential security problems
related to Skype, I am informed that Knoppix users might be better served
by free software alternatives like Google+ Hangouts, standard SIP applications
like ekiga and linphone, or XMPP-compatible programs like Pidgin.
All of these have secure and open protocols, and best of all, are already
included-in, or at least freely available and applicable-to Knoppix.

This intends to amplify a hint Capricorny introduced back at post #9.