I think it’s a nice bit of commentary that proponents of centralized power like Emperor Palpatine or Darth Vader have such a penchant for big, planet destroying weapons like the Death Star.
The Death Star had several fatal flaws.
First, don’t put all your eggs in one basket. While the Death Star is big and powerful, it’s only one weapon. With so much of the Empire’s resources wrapped up in it, all the opposition has to do is destroy one weapon to seriously weaken the Empire.
Second, it’s one weapon with a fatal flaw. In a universe with people who can use the Force, don’t build a space ship the size of a small moon with a lone, unprotected vent to the main reactor core. C’mon. Perhaps the Emperor thought he had eradicated the Jedi, so he got sloppy.
Third, don’t piss people off. Fear is usually a good motivator. But, there’s a tipping point. If you push folks too far, like blowing up an entire planet full of life to make a point about your might, those who remain may stop fearing and rebel.