When infiltrating an enemy stronghold, the place will of course be crawling with guards. So it makes sense to do whatever you can to reduce or eliminate the threat before you begin your assault. So flood the castle by magically diverting the adjacent river, or bathe the installation in gamma radiation.
Just don't reflect too long on the fact that the hordes of faceless NPC guards you're pre-emptively destroying have families and friends. It's better to sweep that under the carpet than to be forced to encounter and kill them all one by one on your rampaging expedition. It also gets you all the experience points a lot faster and more efficiently. A mere 20 XP is a tragedy, but 20,000 XP is a levelling-up statistic.
Obi-Wan: There's the ship with Palpatine on it. We'll land on the hangar deck.
Anakin: I target the force field generator.
Obi-Wan: Metal ships can just fly through.
Anakin: I don't want any resistance when we land. This will suck any occupants into space. Fire!
GM: Um. The force field vanishes, but huge blast doors start closing off the hangar.
R2-D2: Pull up!!
Anakin: Full speed ahead! Me first.
Obi-Wan: Control your aggression, Anakin.
Anakin: You can get through after me. Your ship has a smaller cross-section.
Obi-Wan: And whose fault is that?!