Yellowstone: what's the big deal about it?

I didn't bother reading beyond your initial question and here's my two cents. If you have to ask what is special about Yellowstone then there's no point trying to explain it as you've made it clear you don't have any appreciation for it. It's something beyond the tangible, touchable, politically correctness everyone expects these days. If it isn't obvious to you then no explanation will cure your lack of recognizing the beauty of the place.