Why didnt they use the simpler design of the galactic war from the first game?
Have straight lines leading from our home to the enemy home planet.
If you REALLY wanted some meatgrinder chokepoints, could make it so. You create the "last line of defense" where you know fans are really hitting the shit, and simultanously letting the DSS be more useful.

Oh wait. Right.
It doesnt let Joel have 3 planets invade 1 planet at once.