We have eaten at both RCs at WDW, and regretted both times. Very, very crowded table setup. Constant stream of people walking (actually squeezing) by our table. So loud we honestly had to almost shout to hear each other. Ordinary food, standard fare such as Chilis or other mass restaurants like that. Very high prices, even for WDW. Portions huge, to be point of unreasonably so (I can't think that it's good to bring us so much food). Service was OK, but somehow I'm not the kind who likes the server to pull up a chair and sit at the table with us.
Why does it do well? My guess is the children/teens like it. It is nicely themed, and kids tend not to have a discriminating palate, a cheesburger with a mound of fries sounds good to them. Both are located where there is not a lot of competition for sit down meals. They have a gift shop with RC souvenirs. You can join their "club" and get 10% off your meal the next day.
Fool me once, shame on you. Fool me twice, shame on me. We did go there twice, and should have learned from our first visit.