One thing I really like about the campaigns in both Brood War and Starcraft 2 is that they feel like a realistic portrayal of sci-fi warfare. Realistic military tactics are frequently used throughout most, if not all, of the campaign missions. Tactics that are conspicuously absent in other military sci-fi series, like Star Wars.
When the enemy is holed up in a heavily fortified area (like in the Breakout and Ghost of a Chance missions in Wings of Liberty), instead of just blindly charging all of your troops headfirst into enemy fire, you create a diversion with a small detachment while an infiltrator sabotages the enemy’s defenses.
When you encounter a small group of enemies that are part of a much larger and more powerful faction, you either need to cut off their communications to prevent them from calling reinforcements (i.e. The Harvest of Screams mission in Heart of the Swarm), or you need to get what you came for and leave before the enemy can respond in force (i.e. Most of the missions in Wings of Liberty).
When you need to send troops into hostile territory, your first order of business is to scout the area and secure a foothold, so you often start the mission with a small, elite force to clear a landing zone for your main army. There are countless examples of this in all of the campaigns.
Other sci-fi franchises (again, looking at you, Star Wars) hype up their military commanders as brilliant tacticians, only for those “brilliant tacticians” to make an endless series of brash, suicidal decisions that would elicit a facepalm from anyone with military experience.
Infantry blindly charging out in the open straight into enemy fire, admirals leaving capital ships (And other important assets) unguarded with no escorts, generals failing to perform even basic reconnaissance or information gathering, commanders letting air support go to waste even when they have total air superiority, armies casually landing troops in a hot landing zone with anti-aircraft guns shooting at them… the list goes on and on.
I like that Starcraft’s campaign missions offer a semi-realistic take on military strategy in a sci-fi universe. Wars are won when you fight smarter, not harder.