A major problem was that PCs at the time lacked the ability to display Japanese graphically.

The PC-9801 and other PCs made by Japanese language manufacturers had dedicated hardware for displaying Japanese charactor. PCs at the time were often used as word processors, and users wanted fast Japanese display.

Japanese-specific hardware was able to display a huge number of Japanese characters by writing only 2 bytes per character.

Graphical display requires 32 bytes to display a 16x16 dot character, and the font file is several hundred KB.

In the days of the 80386, displaying Japanese on the CPU was too slow and not practical. It was not until the days of Windows 3.1 that this became practical, after the 80486 became widespread.

https://news.mynavi.jp/article/20130430-windows3/ https://news.mynavi.jp/article/20130620-windows31/ https://news.mynavi.jp/article/20130621-windows31b/

A major problem was that PCs at the time lacked the ability to display Japanese graphically.

The PC-9801 and other PCs made by Japanese language manufacturers had dedicated hardware for displaying Japanese characters. PCs at the time were often used as word processors, and users wanted fast displaying of Japanese.

Japanese-specific hardware was able to display a huge number of Japanese characters by writing only 2 bytes per character.

Graphical display requires 32 bytes to display a 16x16 dot character, and the font file is several hundred KB.

In the days of the 80386, displaying Japanese on the CPU was too slow and not practical. 
It was not until the days of Windows 3.1 that this became practical, after the 80486 became widespread.

https://news.mynavi.jp/article/20130430-windows3/ 
https://news.mynavi.jp/article/20130620-windows31/ 
https://news.mynavi.jp/article/20130621-windows31b/