Quite a few English and Russian Cyrillic letters unify just fine. E and A unify, and have identical lowercase forms, e and a. They don't really have different meanings, no more so than the letters E and A in English and French. T is more interesting: it has the same phonetic sound, but a different lowercase appearance: t in English, т in Russian. In this case, unification would be pretty terrible.
For simple alphabet-type languages, the basic rule should be: if the uppercase and lowercase look the same, then unify mercilessly. P (English) and Р (Russian) should unify even though they represent different consonants. But not V (English) and В (Russian): they sound the same, but have totally different graphemes. On the other hand, unifying B (English) and В (Russian) does not make sense: the lowercase forms look different: b (English) and в (Russian).
Sounds like the major problem with Unicode (and the author's complaints) was always where to draw the line. Han unification went too far and included too many characters that look different. With other languages, some common combinable characters were forced into diacritic representation rather than getting their own code points. To me, the first problem seems way more serious.
For simple alphabet-type languages, the basic rule should be: if the uppercase and lowercase look the same, then unify mercilessly. P (English) and Р (Russian) should unify even though they represent different consonants. But not V (English) and В (Russian): they sound the same, but have totally different graphemes. On the other hand, unifying B (English) and В (Russian) does not make sense: the lowercase forms look different: b (English) and в (Russian).
Sounds like the major problem with Unicode (and the author's complaints) was always where to draw the line. Han unification went too far and included too many characters that look different. With other languages, some common combinable characters were forced into diacritic representation rather than getting their own code points. To me, the first problem seems way more serious.