Not too long ago I was playing through the Zelan and Kuran parts of PSIV. Zelan is a pretty simple place, with only two parts. There's the entrance where the ship docks and the control room. That's all. Kuran on the other hand is much bigger, with several floors. It also has a stealth system that prevents you from going there until you have an item from Zelan.
So, what's up with that? Zelan is supposed to be the center of the environmental systems, right? Why is Kuran so much larger and better defended? It's almost like the place was designed just so the system could be taken over.