Most Helpful Girl
You sound like you are the minority in this because most Western men prefer Western women.
Most Helpful Guy
It's because of modern feminism. Too many Western women are concerned with proving that they can do what mean can do. They want to go out and have careers and choose their own path without having the obligation of a husband or a family "holding them back". They've lost family values and they despise traditional gender roles. Women in other cultures still maintain this value and that's what makes them attractive to Western men.