This is the stablest conformation of ethane, since it maximizes the angle between the mutually repulsive H’s. (What’s interesting is that apparently the precise cause of that repulsion is a matter of dispute.) Perhaps it’s the case, and a quick bit of googling suggests I may be the first one on the intertubes to speculate about this, that the baseship’s shape creates some similar stabilization in whatever field or mechanism the ship uses to do FTL jumps. This would fit with the Cylons’ being more technologically advanced than the Colonials, and with the idea that their technology may be more ancient than is commonly supposed, what with their having been to, and perhaps even originally coming from, Earth.