I agree.
However, when you have 200,000+ POS machines, management wants an AV.
I hate McAfee, I hate using a AV instead of isolating a machine from removable media and the Internet. I hate spending money on AV when we could use it on something else. But when a franchise manager on the other side of the world lets one of his employees use the wifi or a printer or something, I'm glad there's an AV to protect my ass. Even though there shouldn't be a way the POS machines get a virus, the AV is kind of like car insurance: It protects you from accidents, costs too much money per year, someone else forced you to get it, and in the end when something shitty happens it kind of saves your ass.