I've never had full hook up sites. Electric only. 95% of the time the DW and I will use the CG showers but almost always use the TT toilet, Mainly as a water saving measure.
What I have an issue with, is guests having to pay to visit. I can't speak for everyone, but if and when we have guests, they are not a drain on the campground. General maintenance and upkeep of the CG gets done whether my guests use the facilities or not. Most state parks I visit, have times during the day when the restrooms/showers get cleaned. They clan them whether 100 people use them that day or 2. Its not like they have to hire extra staff because i had a guest in the area stop and visit.