But bitcoin needs to be transformed back into a currency at some point to use it. There is no point in a wire transfer if the person at the other end isn't going to use it.
Usually you need something other than USD on the other side of an international border. In which case, USD to BTC to XYZ is very likely to be cheaper than a wire transfer.
I've been doing it myself for years. You have to use limit orders on cheap exchanges (not brokers!) and sometimes wait for the spread to close but you can usually get it within 25 basis points of spot.