> I'd love to see optional typing in Python, I wonder if there is any official reasons about why it never got introduced.

Here are a few from Guido himself (not really anti static-typing, but just walking you through pros/cons as he sees them). Great reads:

http://www.artima.com/weblogs/viewpost.jsp?thread=85551

http://www.artima.com/weblogs/viewpost.jsp?thread=86641

http://www.artima.com/weblogs/viewpost.jsp?thread=87182