The mish-mash of katakana, hiragana, kanji (& their crutch furigana) plus romaji in Japanese sort of signifies how bad of a fit that script is to their own language and its use. In many ways it feels like throwing rocks before one's own feet.
I would be more surprised that the Japanese haven't done more to clean this up if it weren't for the cultural conservatism deeply embedded in its society.
If anything, the Japanese writing system is very elegant in terms of information flow. In a general sense, each script has its use: kanji for content (meaning), hiragana for function (grammar), katakana for foreign words and sounds. Of course, there are many exceptions to that, but the mix of scripts has benefits for parsing text.
Obviously, the Japanese writing system is not a single constructed system like Hangul, but I don't see any reason why it is inefficient (aside from, perhaps, the time required to learn kanji for school children).
I think it was linked to dyslexia and languages with spelling and maybe japanese, and how china simplified it's characters led to higher literacy, although that might have a few confounding variables.
[1] https://en.wikipedia.org/wiki/History_of_education_in_Japan#...
No, actually there was two pushes in modern times. One advocating the use of romaji (or even French) which did not succeed.
Then there was a set a post-WWII reforms that aimed to simplify the script by: standardizing kanji use (eg 言う instead of 言う or 云う), standardization of kanji readings (当用漢字), kanji stroke simplification (新字体), dropping the old kana usage (旧仮名遣), standardization of kanas themselves to get rid of 変体仮名. The convention also shifted from using katakana everywhere where kanji are not used to the mix of kanji/hiragana/katakana of today. So yes, the Japanese script changed quite a lot recently.
There is also an advantage that most foreigners do not realise. The mix of Kanji, Katakana, Hiragana create natural delimiters in the sentence and make spacing useless.
Reading Japanese fully written in Hiragana is currently much harder due to the lack of delimiters between words. The mix of hiragana, katakana and Kanji allow a very high density per character.