"uwu speak" is based on 19th century upper classes and became stock in anime. It stems in turn from the Japanese fascination with the European elite, sailor uniforms for example are based on British royalty dressing up their kids in sailor outfits.

This fascination with the west in turn stems from Japan's ancient debates about superior races. They were once rather humble and loved and imitated China as Rome with Greece, but after the Mongol invasions and their own invasion of Korea and piracy in China this soured. They then believed they had achieved harmony under Edo and a deep sophisticated culture, of course shattered by the west surging ahead in the industrial revolution.

Their view of their own superiority was mocked by their new chattering liberal middle classes, yet at the same time they were shocked by western views of white superiority. Thus they set about trying to figure out what made white people tick, speculating big eyes gave them a wider view of the world whereas the Japanese became perfectionists. Thus they set upon adopting western technology and artificially seeking new things and innovation while maintaining Japanese culture.

Every Japanese person thus had a western suit (or sailor suit for students) and a ceremonial kimono, the external world and the internal world. In theory the Kimono was the real Japan, but over time the Kimono became the costume and the suit the real Japan.