Not unifying them means that the fonts automatically work when you mix text/names written in these alphabets. It also means that mathematical/physical/chemical stuff (that typically uses Latin and Greek letters together) will just work. There is a similar reasoning behind all the mathematical alphabets in Unicode.
Furthermore, Unicode was supposed to handle transcoding from all important preexisting encodings to Unicode and back with no or minimal loss. Since ISO 8859-5 (Cyrillic) and 8859-7 (Greek) already existed (and both included ASCII, hence all the basic Latin letters), the ship had definitively sailed on LaGreCy unification.
On top of that, CJK unification affected so many characters that the savings would really matter and it happened at a time where the codepoints were only 16 bit so it helped squeeze the whole in. All continental European languages suffered equally or worse back when all their letters had to be squeezed into 8 bits /and/ coexist with ASCII.
> Not unifying them means that the fonts automatically work when you mix text/names written in these alphabets. It also means that mathematical/physical/chemical stuff (that typically uses Latin and Greek letters together) will just work.
These are already completely separate symbols. Ignoring precomposition, there are at least 4 different lowercase omegas in unicode: APL (⍵ U+2375 "APL FUNCTIONAL SYMBOL OMEGA"), cyrillic (ѡ U+0461 "CYRILLIC SMALL LETTER OMEGA"), greek (ω U+03C9 "GREEK SMALL LETTER OMEGA") and Mathematics (𝜔 U+1D714 "MATHEMATICAL ITALIC SMALL OMEGA").
Furthermore, Unicode was supposed to handle transcoding from all important preexisting encodings to Unicode and back with no or minimal loss. Since ISO 8859-5 (Cyrillic) and 8859-7 (Greek) already existed (and both included ASCII, hence all the basic Latin letters), the ship had definitively sailed on LaGreCy unification.
On top of that, CJK unification affected so many characters that the savings would really matter and it happened at a time where the codepoints were only 16 bit so it helped squeeze the whole in. All continental European languages suffered equally or worse back when all their letters had to be squeezed into 8 bits /and/ coexist with ASCII.