It is not just america, people shit on every country but I find americans are the more american centric than other people are centric around their countries. In fact I would say you find people outside of america who are very american centric. To be honest I am quite american centric, born in the UK, grew up in South Africa and spent most of my life online and speaking with americans. I want to move to Florida as well, so I think americans are pretty important when it comes to culture in the modern world. That being said many people in Europe are also very centric around their own countries. Some call it little world syndrome.

So that being said, people are critical of the US but I don't think any more so than other countries. Relative to US cultural spread it is probably not that greater than other countries bar the criticisms around wars. However UK and France are equally criticized for wars and UK and Spain for colonialism. It is all relative, but no surprise an american would think they are "most" criticized.