Maybe we should start building cubes and use block colors to paint a ship on each face?
These would not only be cubes! They would be pictures
If we gonna limit the cross-section of x/y axis of ships by featuring long thin ships, we also discuraging RP interiors.
If we make a rule that ships have to be at least stretched to 3x:2y:5z, we get borg cubes with a few 1 block thin spikes on each side.
The only way to un-limit creativity because of efficiency is, to make hull in stretched ships work as efficient as if the ship would be a cube, if not more efficient.
For example give us a weapon that pierces through a whole ship. Now flat ships which don\'t face this pierce-ship will be a lot better.
If we have shotgun-weapons (spray out firepower), flat ships facing this shotgun-ship will be better.