Stocking a ship up with explosives seems a bit stupid when you've got a perfectly good warp core you can overload seems reckless. What if they got hit during a battle?
Think about it: the warp core breach scenario is MUCH more destructive. It would damage or destroy anything within a wide radius. It could have destroyed V'Ger in TMP, so if they were going to steal the Birg of Prey, and survive on the planet below, it wasn't an option.