Adam,
I have 30 cameras in my DVR. To me, the whole point of the DVR is to have a video "server' to capture & record video as a system and a single point of remote access.
If I had 30 IP cameras, I would need to assign IP address to all along with different UDP port numbers to be able to view remotely. I would then need to open a browser for every camera. Then I would still need a server and a fast ethernet switch to record. I'm sure there is software to solve the multi-browser issue, but I don't see how this would be any easier or less expensive.
Also, cameras typically need two cables, one for the video signal (coax for baseband video and CAT-5 for IP) and power (some have another cable for sound). Even if you go WiFi, you still need power...so the whole cordless thing is mute.