Thank you for your detailed response. I now have a better idea about where your question is.
It's not a good idea to generalize (do not ever, ever, make general statements!
). I'm sure there is a range of opinion from the most positive to the most negative about NYC, just like you would expect. But, surely, I agree that it seems like the proportion of people who have a very favorable opinion about NY is very high. I think this has been the case for a very long time (decades), so, the idea of a fad seems unlikely. It is very possible that NY is so unique in its characteristics that it breeds people who can only feel satisfied there. But, that doesn't explain similar opinion from people that come from other places. I have known a couple of people/ tourists (literally two), who didn't like NYC. One felt overwhelmed by the crowds and the pace. One didn't like the dirty areas of the city (!), including subways and streets. Most people talk about the diversity as one of the most interesting features. But there are all kinds of associations with movies, for example getting to visit places that were depicted in famous movies and the like. There is so much variety, that it is indeed difficult to think that anyone wouldn't find a few things, at least, as very interesting. I never had an impression that people were saying that they liked the city because it was the cool thing to say, although I'm sure there's a small number who would do that.
I think I responded to much of the above at the beginning, when I first visited. Later I started to appreciate the city's "personality". I'm never surprised when I hear that others love NYC. It's so easy to understand and relate to it.