Comment by thaumasiotes

I definitely agree that uninterned strings are important. All I'm really trying to say down here is that there are many cases where you have a hash table which uses strings as keys (as an implementation detail), when (conceptually) it wants to be using symbols.

(And on a less fundamental level, the particular Java String class is less string-like and more symbol-like than most string types, and this appears to have been done intentionally.)