"...Apple television wasn't launched exclusively in the US first, [because] content rights can be a massive burden and have to be managed on a country-by-country basis."

It's because Apple wants utter complete control over 'every' aspect of entertainment that comes through that device. Seeing as this is some new territory, there are going to be some bugs - so what better than to keep it home, where you can keep your lawsuits safe & sound.

Then when it comes time to start pushing your copyright agenda on countries that don't follow your policies or laws you can really cram it up their collective asses, be it legally or financially.

Because you just know there are rabid fans of your garbage hardware & retailers will crack in order to get the goods in their stores/territories.