This is a great business model from the standpoint of making profits (less so from the standpoint of ethics or consumer satisfaction). Most people don't travel internationally very frequently, and region locking is not something that's marketed, so they only discover it when they actually travel, and then they're forced to buy another phone! Forget region locking, can't they inflate their profits further at their cus…
The smarter folks buy a cheap $30 GSM/CDMA phone before the trip, the even smarter ones have a world phone and confirm it's capable of taking foreign sims (though having a fallback $30 GSM phone isn't a bad idea).