I think people have a right to complain once in a while on here because this is the only place most of us really have to vent if we have a problem. It may blow things out of proportion as to how much we complain, but if you met us in real life I'm sure you'd find we actually complain very little. It also depends entirely on a person's circumstances whether or not they feel they have to complain at all. Somebody might not like the area or the house they live in, someone might be in a difficult situation, etc.
And when it comes to most Americans feeling superior, just take a look at the Brits and you'll see how much of a superiority complex THEY have, even amongst people in their own country (English v Scottish especially
.) And I definitely agree about the French thinking everything about themselves is the best... I've been to France and I've definitely witnessed it firsthand.
I think Americans and British are just as much to blame when it comes to complaining abroad. Just go on any British expat site and you'll see them complaining just as much, or more. And when it comes to going abroad as tourists, I'm sure you've heard that Brits have unfortunately made themselves notorious as well for being drunk and very badly behaved, especially when there's football involved. For example, recently a Scottish friend of mine told me her friend visited Spain and an English guy in a McDonald's asked if he could kiss her, and when she refused, his friends literally waited for her outside and punched her. Then again, Americans have a tendency to be too loud and come out with stupid comments.