If you use USD and want Yen you don't necessarily have to exchange them. You can start working for Yen. It's the same with bitcoins. You don't have to buy them you can just start services to earn them. I like it better because then you don't have to give out your ID to some online company!
That's an extremely limited niche, though. It's like selling stuff for bitcoin--your market is very small. It's better to earn fiat and buy bitcoin. And fiat is more stable. Would you really want your paycheck in bitcoin?