I think they had to add weight... so.. somebody thought that this was the best place for it...
Arguably the best place would be half in the bows and half in the transoms. This would increase moment of inertia and reduce pitching.
It would decrease the frequency of the pitching but increase the distance it pitches - which may not be favorable. The traditional school of thought is that it's better to reduce the depth of the pitching since the waves are going to help dictate the pitch regardless of weight position. It doesn't fit 100% of the situations, but I have understood that it is generally better to have the weight centralized.
