I have no problem with it as long as it is an option. Kids, animals, bikes, toys and even fire hydrants are small enough to escape the rear view mirror.
My '04 Navigator has the radar warning system. Some of the Nisssan and Infinity SUVs use a TV. It's really useful when backing up in a parking lot or backing up to a boat trailer and trying to make the hitch connect. In parking lots the radar works for soft objects like small children and hard objects like shopping carts. For trailering the TV is better than the radar since it gives a direct view of the hitch ball and the trailer.