Im not sure, its probably to do with them offering the movies at different prices in different regions. It prevents someone from say buying 1000 DVDs in Malaysia for $10 and selling them in the U.S. for $20 for example and trust me, some retail shops would do just that.
In the case for games it doesn't really matter so much as they are roughly the same price everywhere. Its not something which Microsoft dictates anyway... If theres a region lock its the publishers decsion.
http://www.play-asia.com/paOS-14-71-fc-49-en.html
See?
http://www.regionfreegames.com.au/
They exist...
Tease.







