> So you think that the letters in the Greek and Cyrillic alphabets which are printed identically to the Latin A should not exist?

Yes. Unicode should not be about semantic meaning, it should be about the visual. Like text in a book.

> And, for example, Greek words containing this letter should be encoded with a mix of Latin and Greek characters?

Yup. Consider a printed book. How can you tell if a letter is a Greek letter or a Latin letter?

Those Unicode homonyms are a solution looking for a problem.

What about numbers? Would they be assigned to arabic only? I guess someone will be offended by that.

While at it we could also unify I, | and l. It's too confusing sometimes.