I'm not sure the correlation is technical proficiency by itself, I think it's based upon a critical mass of your social circles using iMessage or not using iMessage. If you choose to, you can probably make a correlation between "technical savviness" and a user's choice between Android and Apple, but I don't think that is a deciding factor in who uses iMessage.
The reason people throw fits is because the experience between a group messaging together on iMessage is exceptional - this experience breaks down when even one of your friends in the chat doesn't have an Apple product. They aren't able to send or receive the majority of the "chat add ons" iMessage provides. I'm sure making the bubbles green vs. blue only helps to stoke the "us vs. them" fire.
I consider myself to be a reasonably technical user and still prefer to message with iMessage since I know the experience will be the same for everyone I'm chatting with. Yes, we _could_ all start using WhatsApp et al, but if 8/9 of our group message is on iMessage, why would we?
