Convenience. It may cost like a mofo but there really aren't too many other options in certain scenarios.
Yes. Over and over I read above that BTC is better (low costs). While that (low cost) is true, in places I care about (in Peru, in my US city, etc.) dealing with BTC -- buying and spending -- is very clumsy.
Again, it looks like we need the "Network Effect" to kick-in, once enough players are doing BTC, then it will win vs. Western Union, etc.
Unless BTC is badly flawed... Then you will have to pay WU the fees. You want money transferred somewhere? Pay up.