HN user
These are all centralized companies - if they go out of business what happens to your money? What if the company decides to print more of this money for itself? Napster went out of business becasue the government shut it down. Bittorrent is still going strong. Bitcoin is p2p like bittorent. There is no central point of failure.
And how will they buy them? If they started buying them all the price would skyrocket and people would be more likely to hold onto them. And which government? The Chinese, The Russian the US? We'd see all nations suddenly rushing to buy bitcoins, and I'd be a billionaire.
I've transferred several thousand dollars worth of bitcoins in the last few weeks to a Chinese bank account - the exchange I bought them on didn't know what I wanted the bitcoins for. And the Chinese exchange I sold them on didn't know where I got them from. The act of buying the bitcoins contains no information about their future use. The fees were much lower than Western Union, and since Bitcoin prices are volatile I actually made money on most of the transfers. Bitinstant.com already allows you to send money to anyone in the world using paypal via bitcoin anonymously.
Edit - the point is that bitcoin makes it possible for individuals or small companies to move funds to virtually anywhere in the world. A big multinational corporation facilitating this becomes unnecessary. At some point it will occur to people just to move the bitcoins and not bother converting them to a local currency.