This was interesting. I've definitely noticed this in Japan too. Especially for myself, as a foreigner who only started learning japanese later in life, due to using mobile and computers for typing, I have no clue how to write the characters.

But even my Japanese wife struggles.

Unlike Chinese, Japanese also has a phonetic character set (hiragana) which can be used to spell all words but due to the high number of homophones (because of few base phonemes), this can be ambiguous and hard to read too. So usually Kanji (Chinese characters) are used for main words, often similar to those in Chinese.

I am able to recognize the characters when reading even though I cant write them. When typing, Japanese keyboards let you type with phonetics and then they offer kanji words that match the phonetic word you typed. So all you need to do is pick right kanji word/character to replace your phonetic hiragana.

I think this is the reason people are forgetting, or never quite gaining, the ability to properly write. Its a different type of memory/recall.