This is a good question.  I think the most simple answer is "because they can."  It is perfectly fair and acceptable for a filmmaker to insert their own ideas into a film.  Whether or not you agree with what they have to say, they have a right to say it.  A lot of movies are thought of as offensive because of their sexual content or they express an idea that is out of normal moral boundaries.  I'm not trying to endorse any kind of racism here, but you have to realize that not every country is like America.  We look down on racism here, but other countries do not.  One thing about watching movies from another country is that you are getting an insight into another culture, and that insight does not necessarily have to be a positive one.