Just to wade in on this - I wouldn't let the lack of campaign put you off. Think what a typical mission in a space based RTS would be: destroy this, protect that, wait for reinforcements then go do whatever. Sounds like another day in the Sins universe! I mean okay, there's the reward associated with revealing the plot (if it's a good one) and at the moment, that's very much something that's left to the imagination. They sort of set the backdrop, introduce the factions, then you kind of fill in the blanks.
But the gameplay? I honestly don't believe it suffers due to a lack of campaign. There are missions all the time! Like when your outermost colonies start getting chipped away at by enemy/pirate attacks, and you have to get your main battle fleet there in time to prevent the outpost from being lost, but in the process another faction takes advantage of you being distracted and leaves your homeworld in tatters. So you end up being pushed back to one of your other planets, all vengeful and super pissed, and you might even rename if after your old homeworld in honor of it lol it's fantastic stuff if you just let your imagination go wild.
All of this said, IC could use the current Sins experience to introduce the 'players' (Advent, TEC, Vasari) and the game mechanics, then create a storyline that incorporates them all as an added bonus later on. For now, I love it as is 