The reason, I have come to the conclusion, is that everyone in Germany or China watches American shows to learn the language of English. Even though English as such, is generally from England (using the word "English" to mean "the language from England").
Having said that, there has been a few stories of British teachers being told to teach in the American way of pronunciation and grammar. Which wasn't (technically) what they had been employed for, in the first place....
So, with Germany and China, it is understandable that they would use the Americanisation of English and find it easier to understand. Now, when it comes to Essex people, that isn't so nice to hear, but then it happens mainly because they watch American films and shows.
Reading Bill Bryson's book about the English language confused me quite a bit until I figured out that it was basically written in the late 80's/early 90's. He was saying words that (are now) American, but stating that they were only spoken by the English at that time. So from that, I gathered that fashion changes with Americanisation of words and may rise and fall due to people using them to either differentiate them from the other group, or to include themselves in the group.
Although, its annoying sometimes.