This OID reports the actual MAC address in use by the launched, deployed instance of an iSCSI vNIC as it actually runs on a server, as opposed to the vNIC's policy-level definition (IScsiLCP), the deployed iSCSI vNIC instance running on the server. An admin cares because this is the real, operational MAC address that will show up in switch MAC tables and DHCP leases, which is what they'd search for when tracing this vNIC's traffic on the network. For example, tracing an unexpected MAC address flapping between two switch ports, an admin would compare it against this addr value on each IScsiLCP instance to identify which server's iSCSI vNIC is involved.