People only think that because Paris has an image of being "sophisticated", so all these tourists go there, go to the "Frenchest" cafe they can find, and just sit and pretend to be "that person" for an hour, quietly.
You can sit and watch the world go by near the beach I live close to. Different environment to Paris --- no fancy buildings, and definitely not sophisticated --- but I've been to Paris 3 times (once with friends), and I went to 2 cafes and sat there with them, chatting a bit, drinking wine while being silent, had bread with something on top that didn't taste good, and i'm sure it made them feel really good somehow. It just made me feel like a tw*t.
When I go to the beach and sit and have a drink, or lie down in the sun, watching people surf, swim, or run around, or even taking photos near one of the beaches or near the lighthouse, I don't feel like such a phoney. I'm there because I want to be --- because going there and doing these things is just a part of my routine. If I go to France and I schedule in "3:00 pm: Sit down and watch the world go by", I just feel like a total poseur. Do that sort of thing when/if you want to. If you're only doing it while in Paris because you're in Paris, it probably bothers the people who are there because they have to put up with 1 or 2 Americans who just sit there and pretend to be doing what they're doing.
I don't want to be a Holden Caulfield, but sometimes, that's how I see the world and some of what we "have" to do just because we're in a place like Paris.