I don't exactly think that is the way to go. Dark for dark is stupid. See that Superman Movie. Star Wars was "lived in" not "dark and gritty" to me.
The power structure of the empire was severed. There should have at least been a bright time, a time for the republic to consolidate power and fight the empire remnants. Even the books realized you can't kill the empire completely. Killing a fleet of star destroyers, 2 super moons, a Super Star Destroyer, and thousands upon thousands of sortie fighters and troops shouldn't be hand waved away. If there is a unknown threat...such as a dark jedi with a mask finding a source of power and starting a war, like KOTOR, I feel that would be the way to go. Not "everything is still shit because gritty"
I swear to god Watchmen and Dark Knight Returns ruins everything. Comic Book Dark and gritty, morphs into Comic Book Movie dark and gritty, morphs into High Fantasy/Space Opera Dark and Gritty.
You can be mature and not be "everything is awful omg". Your first movie can't be Empire Strikes Back..why would you want to invest your time being depressed unless you can establish that the characters are likeable and you want them to succeed? There is so much of the universe to put on the screen. KOTOR 2 has the most interesting take of any EU, because it actually talks about what the force is and how the two sides are just means to an end. The Bad Guy just wanted to spit in the face of GOD.