Yeah that's great for new code. What about all the old code people have written and they want to upgrade to the new version of the language? `\{` used to be invalid syntax for the string, so if they add meaning to that syntax then it won't break old code. There's a lot of extant code for Java.
"IDENTIFIER, PERIOD, LITERAL" is also invalid syntax before this JEP, and it's the only way to enable string templates. The processing of untagged string literals is not changed.
