Re: I think it's a reasonable idea.
"An IP address at any one moment in time does point to a specific connection point, and therefore a fixed geographic location."
My public IP address does indeed provide a fixed geographical location... five hundred miles from where I physically am. Not surprisingly, this is because that's where my ISP is - as you mentioned, their LOGS might provide my location barring other factors, but a dynamic public IP may mean nothing in and of itself. This is before taking into account address spoofing, proxies, and Tor. As for identifying a user by IP address - can you really prove it wasn't someone spoofing my address, cracking and piggybacking off my wireless connection, or a significant other, m'lord?