In the opening sequence of Revenge of the Sith, Obi-Wan and Anakin launch an attack on General Grievous' flagship.
When they're attempting to enter the hangar bay, they blow up the shield generator to allow access. However, when the shield opens, the air rushes out and an emergency hatch slams shut.
Why was this hangar pressurized to begin with? I imagine one of the main benefits of using droids is that they can operate in depressurized environments, and large sections of the ship don't have to be pressurized.
Is there an in-universe explanation for why such a large space was kept pressurized in a combat situation?