One can travel abroad and spend their bitcoins there, where it is legal. Or he can just sell it in an international exchange and move the money to an bank account in another country.
While you're right that one can travel abroad for this, most won't do it. Of course, if one is already rich in fiat, he does travel a lot and can do this, or doesn't even care much about bitcoin. But others, unless they live near the border,... not much of a chance. They may have the holidays and everything in-country. And I fear that this is the people whose life can be changed the most by bitcoin (for example by getting easier, better paid jobs over the internet - just in this case they may need to be part time or only partly paid in bitcoin)
Having account in international bank or a bank abroad may not be possible or allowed everywhere. But maybe I'm wrong. And anyway, too many don't have the knowledge and means to open such an account (I expect that most banks will need the people go in person open the account, for example)