Mandatory how?  Who will enforce this rule? This is a decentralized, global technology. Anybody anywhere, with some software engineering knowledge, can create their own wallet software and make it available for others to use. How are you going to force every programmer in the world that creates any type of wallet software to require all of their users to provide 3 addresses? Are you going to employ a police force that will hunt them down and arrest them? Will you also arrest the people that choose to USE a wallet software that doesn't require 3 addresses? What if someone doesn't have any friends or family that they trust? Do they get to use bitcoin?

Bah. You want to use a wallet with a multi-sig system? Go ahead, nobody is stopping you. But you aren't going to force your personal preference on the entire world.