system
Given the following post, respond as if you're commenting on Reddit:
human
[Star Wars] Why does the the republic/empire change the look of there troops/ships/fighters so often? When other factions rarely (or never) did, like rebels and the trade federation.

Seems like they are always changing up troop armor and star ships. Changing out millions (billions?) of troop armor and thousands of star ships can't be cheap. Does the republic/empire lease and not buy?
gpt
Evolving requirements.

The initial launch of clonetroopers came from and were at least in part trained by -- or had their training regimens shaped by -- Jango Fett. Their armor bears many similarities to his own armor, no doubt due in part to the nature of what he was accustomed and trained to do.

Fast-forward over the course of the Clone War and the initial launch of the clones has now had time to identify field-tested flaws in the original armor design. In order to ensure maximum effectiveness of its troops, the Republic continually refines the armor to account for these deficiencies and also to build-in new features that troops may find useful as the war progresses.

During the Imperial transition period, purpose-grown and designed clonetroopers saw decreasing use in favor of somewhat more conventionally sourced and trained stormtroopers. The Clone War was over; the stormtroopers' purpose wasn't fighting a massive symmetric war, but rather peacekeeping and asymmetric warfare against guerrilla resistance forces. This calls for different equipment, too. War armor doesn't provide what stormtroopers generally need. And, to be clear, what we see in documentary footage is fairly *atypical* of the usual stormtrooper assignments; the Rebellion was *tiny* in comparison to the breadth of security responsibilities the Empire faced.

The same is largely true for ships. A space superiority fighter you purpose-build to fight droid fighters just doesn't have the same requirements as an all-around, quick-deployment, high-mobility fighter. That exact same purpose mismatch travels all the way up the chain to the star dreadnought super ships like *Executor*.