Nintendo didn't always region lock its hardware, but it's been the case on the company's handhelds since the DSi. Apparently Nintendo is reconsidering that policy, however.
As part of a recent investor Q&A, Nintendo president Satoru Iwata illuminated Nintendo's evolving position, as translated by NeoGAF member Cheesemeister.
(Cheesemeister has been a reliable source for translations in the past.)
"The game business has a history of taking a very long time with localization among other things," said Iwata, "such as having to deal with various issues of marketing in each particular country, or games that have made use of licensed content that did not apply globally, and had all kinds of circumstances, so to say, that region-locking has existed due to circumstances on the sellers' side rather than for the sake of the customers. In the history of game consoles, that is the current situation. As for what should be done going forward, if unlocked for the benefit of the customers, there may also be a benefit for us. Conversely, unlocking would require various problems to be solved, so while I can't say today whether or not we intend to unlock, we realize that it is one thing that we must consider looking to the future."