Why systems shouldn't be Region Locked

Do you know these games?  The first one is obviously "Ace Attorney".  The second one is the precursor to Elite Beat Agents.  Aside from being on the DS, what do they have in common?

They were only localized due to imports.  For both games, Nintendo noticed a significant amount of people importing the game elsewhere.  How could they do this?

Because Nintendo decided to let people from one region play games from another region. It is the opposite of Region Locking and I don't know why Region locking is so popular.  This increases your install base and it gives you an idea of who else is interested in your games.