We shouldn't change the current default behaviour, people are probably
relying on it.

Besides, doing the right thing is both (natural) language-dependent and
context-dependent. It would be (very) hard to come with an
implementation catering to all needs. Perhaps a dedicated typography
module, but str.title() is certainly not the answer.

However, adding an optional argument to str.title() so as to change the
list of recognized separators could be an useful addition for those
people who aren't too perfectionist about the result.