Vista doesn't use WPF. That ended up being one the huge schisms between DevDiv and the Windows group, that
Technically you have one non-beta closed source; Safari gets its 100% from Webkit, which is open source.
Fed troll is fed.
Not a particularly great explanation as to the shortcomings of Javascript other than apparently C-style languages are a no-go with you. Plus it's prototype system is pretty half-assed, so I'm not sure that's even a positive (I'd prefer real prototype setup like in SELF).
I don't recall asking why anyone would want to use another language, though, as that's obvious: language preference. *shrug*
No amount of careful planning will ever replace dumb luck.