European writing system? very funny, do you know chinese? you know pinyin? do you know the pronunciation of the alphabet of pinyin?
Before, we don't use the pinyin to learn pronunciation of chinese charater, later we use it, also make some change, but not replace it, not like you indian.
Do you know Japanese? do you know they also use alphabet to learn pronunciaton of their fifty tone, but originally, they also don't use western alphabet. pronunciation has been fixed, the alphabet is just as a assistance, but not replace it, the difference, I don't think you can understand.
About you said 30% of chinese couldn't speak Mandarin? where is the source? leave the question that what's the chinese language, My grandmother can't speak Mandarin well, because in china, there are too much dialect, someone is like foreign language for people other place, but we use same charcters, and, can't speak Mandarin is always older, now, young chinese almost can speak Mandarin, at least, we can communicate with each other well.
Don't talking about chinese, because you can't understand the magical pictogram, I am proud of it, Japanese and Korean also influenced by it much, of course, you can say Chinese is stem from India,