Up until 'very' recently I thought much as do you, that cubes reigned supreme. But then I was set straight, by many people over the course of days. It took me a long time to really grock what they were saying, but then I put it to the test and built several sample power arrays. Here is the crux. Yes, a cube structure can be very efficient for generating power, but for the same number of power blocks, so is 'any' shaped rectangle if you build your power lines properly. Moreover you need not be constrained to rectangles, you can do the same with wedges, pyramids, etc.. A little bit of imagination can permit you to get every bit as much power into a non-cube as you could get from a nested cube.
Yes, a cube is slightly more efficient when it comes to hull materials, but that only really matters if you are trying to build a permacloak. The cube does have the massive downside already mentioned in this thread. If you run into someone chucking large damage pulse missiles, the cube has conveniently packed all of it's vitals tightly into one space, a sitting duck for big holes. A longer, more spread out ship, especially one with 'roleplaying' space, will loose much less from such attacks.
