USS Liberty is political, covering it as a story would expose yourself to a vengeful lobby group and bring down whatever you happened to preside over.
Wilhelm Gustloff - they were the bad guys, nobody cares about them.
A good story needs time to develop and things to grab your attention, keep you coming back. With that, the Titanic and the submersible story could keep you coming for the drama. It differs from the Lusitania and Empress - they get little note because there was no time for any human stories, just a violent episode and instant death.
And like the sub, when there's no story you create one.