This is a semi-frequent discussion and I'm one of the ones who likes KOA. I'm not brand loyal but I'll pay $10 more per night for KOA. I get the 10% discount so that helps.
The complaints about $60 routinely shift to motel comparisons. I've stayed in Super 8 or similar a few times over the last few years and to say it is an unpleasant experience is an understatement. And if the motel is anywhere other than timbuktoo, you may pay closer to $80. A decent hotel is now $100+ even on an interstate stop (Holiday Inn Express, Hampton, etc) and it seems hotel taxes are worse than campground taxes.
To each his own but $60 isn't bad anymore. Can you do it nightly when full-timing? No. If I'm on vacation with my family, it's not a bad deal and I mix municipal parks with water and electric for $12, cheaper privates, etc. as I go. Just depends on what is available. I've had great experiences at municipal, non-affiliated private, and KOA's that I would quickly recommend to others.
I've camped coast to coast twice on 30 day trips and did not have time flexibility of a retiree. I would say my average nightly cost is around $50. Highest price was in Anaheim near Disneyland. Lowest was a municipal park in MN ($6 if I remember right). Two worst experiences, both over $60/night were a locally owned campground in NE and a Yogi park in WI.