Hi DavidR,
Agree with you in modern times things have changed. If you have to plug and play devices, you better have it on (peripherals). The goals of UPnP are to allow devices to connect seamlessly and to simplify the implementation of networks in the home (data sharing, communications, and entertainment) and in corporate environments for simplified installation of computer components. UPnP achieves this by defining and publishing UPnP device control protocols (DCP) built upon open, Internet-based communication standards (port-forwarding). If you have Media Servers you are ill adviced to turn it off, because with closing down UPnP you would not like other services to be closed. I can imagine it could help towards router security in some sense,
polonus