More important question, does it matter?
Now, I'll admit, I tend to play sci-fi games, often strategy and so on, so I really don't see what it matters. Yeah ok, most of my player characters and NPCs have north american accents but then the games are made there (The notable exceptions to that rule are the Imperial forces in the DoW games, and probably the upcoming Space Marine, who all come equipped with British ones), and more significantly, are often not even from Earth. The one game series which did things slightly differently and which comes to mind was the Lancer games (StarLancer and FreeLancer), but then the division of the Aliiance into it's constituent nations was part of the whole flavour of those games, though once again, most of the characters weren't even born on Earth.
I seem to have gotten off track slightly... Basically my complaint against the concept of asking 'is this country being slighted?', 'is that one being over-represented?', is that ultimately, this is the 21st century. An age of massive inter-connectivity between all nations, where even physical national borders are starting to slowly dissolve.
As such, do such questions really matter?