Both sides stories are presented as you have to save the day.
Strange, in my opinion it looks much different than my version of republic quests. I have to admit that Tatooine is worst with the "OMG, MY LORD, WE NEED HELP WITH THOSE FEROCIOUS JAWAS!", but Balmorra? All I remember was pretty much what I wrote earlier about the Sith spearheading the assault. Did they lose Balmorra?
You are wrong when it comes to Alderaan imho.
What I mean, aside from occasional PC saving some imperial NPCs or doing errands for them, is that most of the quests revolve around one thing - performing face surgery with a glowstick/blaster on everyone who disagrees with the Empire to subdue him while Republic actions are like wrapping a car that falls apart with duct tape so it holds just a bit longer. Rep side Hoth was pathetic, for example.
If it wasn't for the Havoc Squad, it'd just lose one battle after another.
And what does Sith Warrior do in his storyline?
Forgot to add - It's not really like that on Dromund Kaas. You pretty much do errands to hurt the rebelling lord, you get a task(not a plea for help, mind you!) to infiltrate Revanites and as for the slaves.. well, that's the only case of you actually saving someone's *** because of the officer's incompetence.