[ispiked]

This is highly annoying if you're trying to do any sort of DNS based stuff, like run a server from your home computer and assign a domain name to its IP.

And on the internal side; e.g. behind a router, it's highly annoying too if you try to do any sort of IP-based port forwarding or try to set up something like Synergy to share a mouse and keyboard between two computer. MAC address based DHCP for the win, IMO.