Identity based cryptosystems

I did a quick reading on "identity-based" cryptography. The idea was firstly proposed by Shamir in 1994: "Identity based cryptosystems and signituare schemes".
The idea is to get rid of public key exchange protocols, third trusted parties, CAs in an assymetric (public/private) key cryptosystem by using the pre-known id of the users (like email address, social number, etc.) as their public key.