Sounds EXACTLY like how they have done STO. These irritating boxes will drop off of kills, but you can't open them without first heading to the store and paying real money to get a key to unlock these boxes. They will either have crap inside them (Most often then not) or they will have that *one* piece you have been looking for like crazy that nobody has.
It's a money trap and quite frankly, should be illegal IMO.
You've just had your first experience with Perfect World Entertainment, the king of gambling in games.