It isn't just the nostalgia which watching old episodes of the show evokes. I think the quality of the programming was better than anything since. And Carson reflected the values of an earlier generation. He was in television from its early days when the standards of what could be said, discussed, or shown on television were much more conservative. Believe it or not that made for better, more intelligent, more intellectual, and funnier programming. Jokes about sex were more indirect, took a second or two longer for the audience to catch the meaning, and were funnier because of it.
But these shows do evoke feelings of nostalgia in me. I remember these shows. I stayed up late at night as a kid and watched many of them, and later as a young man still living at home, with my dad. I laughed until my stomach hurt sometimes watching Carson during the original airings, and watching them now brings back wonderful memories.