system
Given the following post, respond as if you're commenting on Reddit:
human
[Star Wars] Why was the Death Star laser so much more destructive than it needed to be to kill all life on a planet?

In Star Wars, the Death Star laser is shown to completely vaporize an entire planet in seconds. Why would the Empire waste resources building such a powerful superweapon that requires a moon-sized ship to operate? Wouldn't it be easier to just put enough energy to kill everything? The crust is incredibly thin compared to the core so creating a ripple of energy that melts it should be insignificant compared to the energy needed to vaporize it. The production of the death Star also was enough to take up a huge amount of resources to create so it wasn't a casual choice to make it more powerful. For example a 40k style exterminatus would be more than enough to achieve their goals.

What was the reason for the laser being so powerful? Was it a show of force? Is there some sort of shield that could block a weaker laser? Is there something bigger than a planet they need to destroy?
gpt
Because there’s no kill like overkill. And because they could. 

Tarkins Doctrine was to rule through fear. A battle station that could vaporise a planet would quell any uprising or rebellion (in their eyes) once it appears in orbit.