Complacency is not a good argument: "the majority of people I know use it so it shouldn't be criticized for the sake of convenience". That's what I hear, maybe I'm deaf.
Jitsi or Ekiga or any other type of open technology can effectively replace facebook quite well. They also give you "the psychological benefits of just feeling connected". I would submit that the Internet fills that niche, not Facebook or others like it.
People can use it all they want. Fine, no problem. But to lean on the idea that it is somehow impossible to delete an account without becoming a hermit is, in my view, a complete asinine idea.
I also think it's important to not get off track from my original point which is: It is not the end of your social life if you decide to delete your facebook account (or google or twitter etc.). That is my point.
I emphasize "open" because those technologies are open for review by thousands of eyes. If there are privacy issues it will be known and tended to. Using something like Skype does not ensure your privacy; especially since now it is more centralized and not p2p. There has been many articles released about the privacy concerns of using Skype (wiretapping, China, etc.). I, for one, do not ever want to put my privacy in the back seat for the sake of convenience and I think it's imperative to educate or at least mention the problems with closed technologies that are supposed to be "private".
Jitsi, as far as I can tell, runs on Windows, Mac and Linux. Those platforms are pretty much covered. I'm not sure if it runs on Android or iOS. Though, I'm sure there are people working on mobile solutions (I am, at least). I wouldn't dismiss it so easily. Skype runs like utter crap on Linux systems and while Jitsi may not run all that well compared to Skype, it is at least open sourced and free software so people can work on it.
Email is essentially a social network. A social network is simply, at its core, a system which allows friends/family/other to communicate and keep up to date with each other. In fact, I would go so far as to say the original social network is not Facebook or MySpace but the Internet itself.
Again, I'm not trying to suggest there are alternatives that can completely replace Facebook (or others) convenience factor. Not at all. I am simply saying, you don't need it.