"Han unification" (deciding that Chinese and Japanese characters were 'basically the same' and could be represented with the same set of codepoints) was a terrible idea, yes, mainly brought from the Unicode foundation not being run by people who spoke or wrote either language, and not wanting to "waste" their limited code points in the BMP on languages using an inconvenient number of characters.
Isn't the that point of UNIcode?
To unify all text into a single character set so that can exist side-by-side without messing with code pages?
Isn't this just code pages all over again?