Having visited Yellostone this summer and stayed in 3 campgrounds ran by Xanterra (Grant, Canyon and Fishing Bridge, with fishing bridge being the only full hookup campground), I had no issue with the way they were operated, the campgrounds appeared to be well maintained, the staff that I dealt with were all reasonably pleasant to deal with, though there was a certain bureaucratic paperwork feel with the must read these regulations to you, and get you to agree at each check in.
Now personally I would prefer more full hookup campgrounds, though I am no big fan of the fishing bridge packed in like sardines layout. I think the real need is for more campgrounds at Yellowstone regardless of type, water and electric with central dump station would be great, if they were more spread out like the no hookup campgrounds, it would also be nice if they had more, smaller campgrounds, the size of some of the ones at yellowstone is absurd with a 5 minute drive from the entrance just to get to ones camping loop.
So I am neither for or against concession operated campgrounds, but if this is a way to provide a service where otherwise none would exist, or where we would have only unmaintained dilapidated campgrounds I would pick this. There is a perfect example of a dilapidated campground in a national forest about 60 miles from where I live, 25 or 30 years ago it was a nice lake front campground, now only the boat lunch remains functional, the visitor building is boarded up and falling apart, the dump station is non-functional and overgrown, and the rv sites themselves are being reclaimed by the forest. I drove by and saw it last year and it was in sad shape, I think camping is still allowed there, but it is now no longer considered an official campground, and I suspect maybe only 1 in 5 of the rv sites is still accessible due to overhanging limbs, etc.