1. About what calls more attention from most of the people and make them take pictures; and
2. That most of people tend to repeat cliches an not to be creative.
And the second one show us that the most popular things, places, people and happenings in the world have already been shot.
When I see a very famous and interesting place, what comes to my mind is that, most likely, someone in the world took that picture that I was about to shot, had the exactly same idea and probably was attracted by the same reasons in the same place. And, of course, this picture was, in all likelihood, uploaded to somewhere on the internet.
Why lose my time when I could be simply seizing the moment when I was there?
Pictures won't capture the awesomeness of the moment.