I wouldn't say it's an option: the string's internal representation might be UTF-32, but whether or not it is is transparent to you the coder. (Just as the JS change is transparent to the JS coder.)
However, the Python change wasn't entirely transparent: len() on a string now returns the length of the string in code points, whereas previously it returned the length in code units. Further, previously Python could be built with one of two internal string representations, so len(s) for a constant s could return different answers depending on your build. Now it doesn't, and len returning code points is much more useful.
However, the Python change wasn't entirely transparent: len() on a string now returns the length of the string in code points, whereas previously it returned the length in code units. Further, previously Python could be built with one of two internal string representations, so len(s) for a constant s could return different answers depending on your build. Now it doesn't, and len returning code points is much more useful.