Signum has a big advantage that many other blockchains do not have. Private messages can be sent as plain text or encrypted. They can also be sent as public so that anyone can see them on the blockchain. This means that they can be used more many purposes.
To build a concept with syntax and semantics that, when agreed upon by other participants, can represent a way to introduce tokens that can be sent from sender to receiver and confirmed by other participants over a framework. Pchains, as it is now, is working in a small scale way that you can register and initialize a new private chain and create tx to send to someone else.