Hmm.. In a way, the disadvantage regarding Hive has been best sorted out with the downvote system in order not to promote unhealthy comments.
Presently building your life and connection on Web 2.0 is just like building a mansion on a land that it is not yours. One day, the owner of the land would come and say remove your mansion and go then it would be too late your customers who already knows the location of your mansion to find where you have moved to therefore you lose customers. That exactly sounds like web 2.0 to me.
About twitter, truly they are a multi billionaire company. I don't think they have much interest in decentralisation because if they do, something would have come in place by now. Or maybe Jack is just too picky and doesn't really know what he wants.