Why are continuous code reviews great? Is a flood great because water is good?
People who don't like pair programming aren't merely antisocial, as you contend. There are very legitimate reasons why pair programming may be a bad idea. For one, logistics. Having pairs requires people to work the same hours, sit in very close proximity to one another, get interrupted when someone else needs to use the bathroom, it works poorly with telecommuting, etc, etc. There's something uniquely human about needing some space to work and think, that pair programming does not allow.
It's also pretty established fact that knowledge work (for many people) requires concentration, and the absence of interruption. Pair programming is horrible from this standpoint. You are constantly having thoughts, and then getting interrupted when your pair has a thought they want to share. You'll basically be coding, and trying to hold a conversation at the same time. Concurrency like that isn't helpful for many computer programs, and it's even less helpful for most human brains. It's like context switching on the order of seconds, rather than having an hour or so to work in peace and quiet, and then conversing with a coworker only on demand.
Personality also has an impact. If you have a dominant personality (driver), you'll often have them doing most of the actual coding, with the other person just serving as their typist (which is slower than if the person thinking just typed it themselves). The passive personality may be having trouble coming up with good ideas on their own, because their mind is being constantly re-routed by the aggressive personality.
You can argue all you want that impracticalities like the ones I've mentioned are just indications that the pair programmers need to get better at pair programming. But, that's crap. A good system is one that capitalizes on the way people actually are, not one that forces people to work in unnatural ways.