I only just read this thread, but contrary to what folks have suggested, "ethnicity" is an attribute of all groups within a society / culture. Yes, we often are blind to the ethnicity of the dominant culture, especially if we are a part of the dominant culture, but "ethnicity" doesn't simply vanish.
------ Back on track -----------
You folks didn't mention that "TurboGrafx" was a gray-market item in Europe! This fact was confirmed recently (1-2 years ago) by John Greiner at Hudson. I tried to find my old thread at the Hudson Forums, but they must have gotten rid of it.
But, to get to back to the original question: from a marketing standpoint, it makes sense for Hudson (and Nintendo) to use "TurboGrafx" in Europe since all of the North American English-language media / resources have used "TurboGrafx-16" consistently since the console was released here in the States and now Hudson wants to build on this name recognition. Why confuse matters by using "PC Engine" in Austrialia / EU / UK when most print- / online- media use another name?