i hear ceramic coating is a hoex. not saying it it just what i hear.
I do coatings myself as a hobby and I have ceramic coated my showers, my Mustang and a friend's car and the hydrophobic quality alone sells me on it. It's a measurable amount of protection for the paint so I dont see much to argue with on a scientific front.
Now, some installers probably gouge a bit on price but its labor intensive to correct the paint, buff, polish, etc and then apply the coating. If I was doing it for pay I can tell you I'd charge a premium just because of the time involved.