I think that the global popularity of Western fashion has something to do with notions of perceived modernism versus traditionalism. Western clothing is often thought to be more modern than Eastern* clothing. This is probably because:

1.Its introduction to the East is relatively recent compared to the advent of local fashions that are sometimes hundreds (or thousands) of years old. What is today known as “Western civilization” is much newer than ancient civilizations like China and India. In some communities, Western clothing is used for everyday wear and business, while local clothing is reserved for special occasions (religious holidays, weddings, etc), reinforcing perceptions of Western = modern and Eastern = traditional.

2.It’s considered “secular” (not tied to religion or cultural traditions). Much of Euro-American dress is either derived from military uniforms (ex. many jackets styles), or arose to fulfill a practical purpose (ex. jeans). I’m sure there are examples of prevalent Western fashions that were influenced by traditional or religious clothing, but these origins have mostly been removed from the meaning of the clothing itself.