I am an older hand at this, and I am right there with 2012Coleman. If you have one, great. It can be a nice tool. If you don't have one, do not go to any great lengths to put one in. We still have one in the 45yo coach and I can't even tell you when we last turned it on.
They most certainly are used on the open road. I work for a rather large transportation company and have frequent conversations with OTR drivers. People utilizing RV's may or may not, but it's not a bad tool to have to check on road conditions, etc.
There are a few that still use them, but it's not as common as it used to be. I have 2 of them, but right now I have no idea where they are, haven't used one in years.