This goes back to a historical issue, which was originally created by missionaries. As a native of China, I think I can understand the hardships for westerners to learn Chinese characters. It has gradually become a phonetic notation, which can be understood as the international phonetic symbol of English or Chinese Pinyin. Of course, Japanese pseudonym itself can also be understood as a kind of pinyin. Roman characters can be understood as the pinyin of foreigners. Or some international occasions, such as trademarks, are traditionally represented by English letters, so Roman characters are used more and more.