system
Given the following post, respond as if you're commenting on Reddit:
human
[Star Wars] If a huge fleet can orbitally bombard a planet's surface to dust, even back in the old republic days, isn't the concept of the Death Star massive overkill? It's not like you need all that power to kill people living in the core of the planet.
gpt
In addition to Tarkin wanting to scare everyone, the other advantage of the Death Star is its Nigh-invulnerability. 

A huge fleet can be met by another huge fleet in combat. It can be harried, disrupted, blasted by surface weapons, etc...

The Death Star was effectively beyond these concerns. It's planet killing capabilities were merely the mirror of its (expected) invincibility.  

As they say in IV, the death star is designed to repel large scale assaults, and could really only even be approached -- even absent a fleet escort -- by smaller fighters that should not have been able to hurt it. 

An invincible terror weapon, that no fleet can hurt, that can destroy any target. A worthy crown jewel for the arsenal of any Galactic Tyrant.