The Prophet was balanced and extreme introvertness is not in line with Sunnah; but I don't think it's wrong as people can just be that way without losing the ability to do tabligh/Da'wah, which can come in many ways - doesn't necessarily have to be by speaking to the person and socialising and initiating a conversation. It can be through a website, blog or forum, or by making sure we have excellent Akhlaaq whenever we do meet people etc