American stereotypes of British Guys ?

I just finished watching this war film called pearl harbour. Why is it that in almost every american movie, especially war films. British guys are depicted as being basically, a bunch of posh talking effeminate pansies with bad teeth. There are hardly any british guys which talk or act like hugh grant for example. Its a bit like the equivalent of every american character in a british film being given a ghetto accent. Is this done to deliberately mock british people, or do you really think that we are all like that. It saddens me that the country which i have such a high opinion of which i have even considered emigrating to once i have completed my education, seems to have such a low opinion of the british.