system
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human
[Star Wars] Why do battle droids use external bladders?

Super battle droids have integrated blasters in their arms, why are regular battle droids made with hands and equipped with blasters? What purpose do their hands serve?

External Blasters, not Bladders....
gpt
The regular, tan, dumb battle droids were not meant to be an army that took on the entire galaxy. They were designed to be super cheap bodyguards and escorts, with minimal advanced combat programming. Part of their EXTREMELY cheap design was that they did not come with weapons integrated into their bodies. They do have a slight advantage of being able to wield different weapons to lesser or even lesser success than the cheap guns made for them, but as I've said, it's such a lesser advantage to sometimes be a disadvantage. (Like say they pick up a clone's blaster rifle, but then hold it badly and end up shooting their own arm off)

The Trade Federation never saw fit to spend the necessary money to upgrade them in any way, since it was so much cheaper to produce them in endless numbers and treat them like cannon fodder to take ammunition away from clones and jedi so the REAL battle droids could actually do damage.