Decentralized services put users in control. Companies and products do not last forever. If a company changes its terms, shuts down, is acquired, discontinues a product, no problem – users can take their data and services with them and set up somewhere else – on their own server or at another service provider. Decentralized, protocol-based systems offer users a choice of providers and developers the opportunity to innovate, since developers deal directly with users, not a platform or company.
If we are going to have a Twitter-like service that lasts, Tent is the way to do it. Tent is decentralized, like email or SMS. App.net is just another Twitter.