Nope, I am not saying anything of the sort. I haven't even mentioned anything which hints at removing anyone from anywhere. The OP asked "are Americans over represented in trek?". The answer is objectively yes.
If a group represents 4% of the human race but is shown as being 40% that is an over representation. If you are offended by that I can't help you, the numbers don't care either way, it's still true. We've gone over the real world explanations, they were a given from the word go.
The sensible question in universe then becomes how do we explain this. We could postulate the Eugenics wars may have left America largely untouched compared to other parts of the world, either through some tactical advantage or some diplomatic agreement perhaps.
You're completely right, but if it doesn't matter where you're from, why is every second person from America? Purely on the balance of probability there should be far more Chinese people than Americans.
Yes, Matt said it, and you agreed.
It doesn't matter what the population of the world today, or the percentage of Americans is. The only way to bring in this representative diversity(by non existing in universe nationalities) is to eliminate Americans from Star Trek.
Deep space 9 has 1 "American" captain and his son. Is that 40%?
TNG has Riker
Is that 40%?
Voyager has Janeway
Is that 40%?
Well, I guess in one of these cases it could be. You just have to rid your argument of all those pointless aliens. They don't count, right?
Heck, Starfleet itself...and the Federation Council exist in this place you are referring to as America. We'd better fix that immediately.
Instead of looking at in-universe circumstances and applying ex post facto criticisms of a lacking in nationalistic diversity in a universe which has no national boundaries on earth, why not praise these shows for the effort they did make and succeeded in?
If my own child made a painting when she was 5, and tried to use as many colors as possible, would I pick up that painting 20 years later, point at it and say "Not good enough. You still used way too much blue. Blue is just one of many colors. You have failed in this regard."?
Are Americans in the real world over represented in the film industry? Are American movies over represented each year out all the movies made around the world? Are American films over represented at the Box office?
Why is one "Definitely American" character on a Star Trek show too many?