If you care about Unicode for real, yes.

Rust and Go both don't have a builtin package for grapheme iteration - and many naively (and incorrectly) think that a 'Go unicode rune == "character"' in Go. I assume the same happens with Rust `char` type.

If you care about unicode-aware string sorting (you should), rather than the naive string sorting the Go and Rust standard libraries provide out of the box... then you probably want a proper Unicode library.

I think the only language that gets Unicode 'right' out of the box is Swift, as it actually provides grapheme iterators, Locale awareness, etc. - but it comes at the cost of the language being tied to the (ever-moving) Unicode standard.