[r2vcap]

I believe that's a historical (19th-century) reason. Japan tried to live up to Western standards. They underwent radical changes and adopted Western culture, driven by the significant influence of the '脱亜入欧' (Leave Asia, Join the West) theory during the Meiji era. That's why they adopted a Western-style naming convention for English names (Personal name + Family name).

However, China and Korea didn't modernize as fast as Japan. They didn't have radical changes in the 19th century. (The result is that foreign concession in China, unequal treaties, colonization of Korea, etc.) So they didn't have to change their naming convention.

The reason why Japan is trying to change the English naming convention when they write in Japanese is similar to the reason mentioned above. The 21st century is Asia's century. Japan feels that they don't have to conform to Western standards anymore. They are trying to be more Asian. That's why they are attempting to change the convention to synchronize as if they were writing in Japanese.

I hope this helps.