Chinese people take Western names because Chinese are very flexible and, especially, because the Chinese naming system is quite alien to Westerners. There is a

Chinese people take Western names because Chinese are very flexible and, especially, because the Chinese naming system is quite alien to Westerners. There is also the issue of tones, which is the major hurdle for Westerners. Now as to "you need to learn pinyin and it's rules". Yes, you need to learn and make some effort to pronounce a foreign language. The same goes for any language and it is unavoidable.