I don’t know why, but it’s such a remarkable phenomenon. Many English learners are trying to obtain a British (or American) accent. But why is this important for many students? I don’t know why I should waste my time learning how to imitate a dialect. I don’t care if people hear my Swiss accent and recognize me as a non-native English speaker.
More importantly, they got my message, and I can communicate in English. That is what learning a foreign language should be about. Just immerse yourself in your target language as much as possible, and by the time you improve your communication skills. The more diverse this is, the easier it will be to understand other accents such as Asian English, which is also charming and fascinating.