heh. What's the deal ... the television is always greener on the other side of the ocean? I have a Japanese associate that does the same (he scoffed when I mentioned I got a Slingbox ... he had been using a PC to stream for more than a year), just the other way around.

I suspect you nailed the reason based on configuration. I installed my Slingbox for the first time last week and the installation software did not prompt me for the IP address of the box. Some amount of discovery occured on the local subnet that would likely be impossible to do if you were running on the Internet. I don't know how subsequent configuration changes are accomplished, but the viewer does give you the option of addressing the box using either an IP address or a unique ID that is registered on one of Sling's (?) servers.

Once the device is configured, if you want to make it accessible on the Internet, you need to open up the port on the firewall/router anyway. I've no idea what other services/ports may be used on the Slingbox besides the one required for the viewer, but it'd be a real bummer if it became unusable (DoS) because of the always present Internet noise.

I like your idea of simplicity though -- I had to get a 802.11b/g Ethernet bridge running to connect the Slingbox on the LAN from its location in the family room (the Tivo least likely to be in use during the evening), to the wireless AP to the router.