This development reminds me of WhatsApp’s approach to managing contacts. No invites are needed. if one of your existing contacts is already using BBM, you can just chat away. Such contacts cannot see your BBM display picture or BBM status updates though. You can invite them to become full BBM Contacts. You can block them at any time too. This feature is supported only on the latest BBM updates. I am aware that both BBM for BB10 and Android have it already. Have you updated your BBM app and used this new feature yet?
This is really a reason why you should update your BBM now!!!