That point was not related to information security at all, yet you apparently accuse me of infosec paranoia (the point was about choice, but more on that in end of the post). Security is just an example of the many things that can go wrong when users choices are artificially limited.
This is what matters: with Skype and other communication methods that work over proprietary protocols I'm tied to whoever owns the protocol. If the provider becomes evil, my _only_ choices are to stop communicating totally using this method or continue using the evil provider -- this is not how a free market should work.
You mentioned Google specifically, let's take a closer look at that example: I currently use Google as my xmpp/email provider but the "address" I give people is on my own domain. If I want to change either xmpp or email provider, I can do that by asking my DNS provider to change the relevant records. My contacts will never notice a thing a thing Google doesn't have any say in my decision.
If you can't see how Skype and Google are different from the example above, then I just can't help.
Finally, I hope you realize this isn't about infosec paranoia, it's not about security at all.
It's about being able to choose your service provider -- ensuring that there is a real free market on this level as well. It's great that there is "protocol-level" free market (e.g. Skype vs xmpp vs Facebook chat) but it's important to realize that there should be competition below that as well. If you disagree, would you really be fine with the idea of a single telephone service provider for the whole world?