- UTF-8 is much more commonly used than ASCII (at least I hope so)
- Modern C++ has
u8"", and even in the old days you could easily put UTF-8 in string literals
- consistency —
juce::String(const std::string &)already accepts UTF-8
And we can have an assert that a string is valid UTF-8, I don’t think it is likely that other code pages result in valid UTF-8.