Can someone remind me what the defense of region locking is? Honest question.
Devils advocate,
activate!
For Nintendo some games are tailored for each region, this includes difference in language and often has the strangest translations even between NTSC and PAL regions.
If I recall correctly some games require certain text or characters to accommodate certain accents to text files. This used to be an issue with little 1MB memory carts but not so much today. Voice acting though can cause issues if the whole game is voiced in English/German/Spanish/French/Etc for a lot of the PAL regions this can be very important. Imagining buying a game but finding it wasn't in your language, you'd be pretty cheesed.
Other examples in language include cultural context or slang, for example in Mario Party (6? 7?) one of the mini game descriptions used the word '*****' but in Australia that is a derogatory term against mentally disabled people so they had to recall all the Australian PAL release copies and patch it to be 'crazy' or something.
Region locking from a business perspective is also quite...
good... for hedging your sales by controlling imported products.
Also promotional differences between regional products vary. Nintendo has (correct me if I'm wrong) over 9 different 'Club Nintendo(s)' which all require game registrations from specific regions. This proved very annoying in Australia when some retailer purchased UK versions of games (slightly different boxart, slightly different back of the box text, different language options) but their Club Nintendo points were invalid for Australian accounts.
Then there's differences between region hardware (Remember the 50hz vs 60hz issue?) and differences between controller style, layout and appearance.
There's a lot of stuff that varies from region to region. Nintendo want to control and micromanaged each regions game experience to suit that particular market.
But yeah it's pretty annoying and I'd rather it not be in place.
EDIT: Hey, did you know. The Smash Dojo is also region locked! Differences between regions are reflected in the various versions of the site
http://www.smashbros.com/