I remember DB talking about a game mechanic that they plan to implement (if anybody can find the link they win a virtual gold cannister).
He described the idea of a huge cargo ship with little to no defences, going to a system, and arranging escort from a number of strong fighters to prevent being lynched. As a reward for protection, the fighters would be given either a payment or a portion of the booty.
I think this could be a fantastic game mechanic, once in-game communication is implemented. It would move the game away from pretty simple and repetitive "lone wolf" killing, and into more intelligent, strategic and collaborative play.
So yes, we need these weak-hulled ships to add various gameplay models.