This page is part of the web mail archives of SRFI 75 from before July 7th, 2015. The new archives for SRFI 75 contain all messages, not just those from before July 7th, 2015.
Forcing it to be "\x41 bc" will become unbearably tedious and confusing to readers also used to programming in other languages.
It will become a large source of errors for string literals transliterated from other other language environments.
If the compiler can detect it as an error, it can fix it, at least with the \u and \x escapes. Other languages don't require a delimiter, they either expect a varying sequence of digits or a fixed number. This is more user friendly and trivial to implement.
Cheers, Ray Blaak