Taking hostages is the only reason why pirates can (sometimes) ransom the ship instead of getting cleaned off by PMCs or even foreign militaries patrolling the waters.

A ship without hostages means that a pirate has a good chance of not getting home ever again - the patrols aren't allowed (rightly) to stop a "fisherman" boat in these waters before it's done anything, but once they are on board and making a ransom note, they'd be lucky if they survive to be arrested.