Protocols are most successful when focused on initial design goals.
Protocols get more complicated and less implementable as features are tacked on. We don t want to contribute to creeping featurism in LDAP as it is already useful in email world to solve the global authoratative user directory problem. The LDAP model is sufficiently different from IMSP that it could create unforseen problems. Deployed LDAPv2 infrastructure is missing fundamental ACAP requirements. Upgrading a deployed and much needed infrastructure is far more expensive then adding a new protocol.