What were the other possible trade-offs? I don't really see how lack of round-trip compatibility is worse than what we have now. It's breaking the whole idea of Unicode code points and for what.
This isn't honored; we have many Unicode code points that look identical by definition and differ only in their secret semantics, but all of those points are in violation of the principles of Unicode. The Turkish 'i' is doing the right thing.
E.g. Cyrillic "а" looks the same as Latin "a" most of the time, they both are distant descendants of the Phoenician 𐤀, but they are two different letters now. I'm very glad they have different code points, it would be a nightmare otherwise.
Having distinct code points for Latin capital letter A, Greek capital letter A, and Cyrillic capital letter A is the reverse, separate code points for glyphs that are identical by definition. That's also a mistake.
(Although it might be required by Unicode's other principle of being fully compatible with a wide variety of older encodings. There are many characters, like 囍, that don't qualify to have a code point, but that have one anyway because they're present in an encoding that Unicode commits to represent.)
Why do we then have lots of invisible characters that are intended essentially as semantic markers (eg, zero-width space)?