Why do I need an admin password to change the VPN PPP Password in my keychain? It's MY local personal keychain after all. I can edit other passwords, but not the VPN PPP pasword. See screenshot for details.
I think because VPN is a network interface, your basically changing preferences for that (so that´s a global change, not only for your keychain item). So the same way you need to identify as an admin to unlock "System Preferences...">"Network" for being able to change interfaces, you would need to do that here, too.