I agree there are better things than LDAP. You and I have worked with better and worse things than LDAP.
LDAP though has one thing Netinfo doesn't, people know LDAP. Not matter how bad the configuration is, people will still grok it.
Take Sendmail for instance, now there is a configuration of clarity. Some of the Perl things I've worked with are worse, mainly because of the jack-knife-ness of the stuff.
And we all know (from somebodies comment) how nasty Java can be.
If Apple would have caught on sooner than it did, it wouldn't have needed the $120M from Bill Gates.
No, I am not bitter, just ticked off.