Think about it. The Galactic Empire builds a monstrous armored space station that's 100 miles in diameter and capable of destroying an entire planet with one huge burst from its main weapon, yet the designers left a fatal weakness in the design that not only left the most powerful weapon in that entire galaxy vulnerable but led directly to the main reactor? No shielding or protective plating in between to keep something from reaching the core? Just a long, long shaft straight to the one part of the station that would trigger a colossal explosion and make the whole weapon utterly pointless?
Then the Empire builds another one with the exact same weakness
I can criticize Jedi
for many things, large and small, but I'll forgive it for that. First of all, I get the impression that a station like that needs a main reactor. Second, they were still building the station. They probably would have surrounded the reactor with extra armor and shielded the exhaust port later in the construction. They made up for this weakness by creating a separate shield generated from the planet. Plus, the weaknesses in the station itself and the shield were left there as bait for the rebels anyway.