Re land units, I use them as buffers while the fleet can come and bring relief to a besieged planet. Plus they don’t count against the total for maintenance and they can be mass-produced by planets with lower industrial output. They work well in combination with planetary big guns. From a roleplay standpoint they are quite in line with what I would envision for Star Wars land armies.It would completely rewrite the game but Kobayashi's Civ2 landmark Star Wars: Insurrection worked that way: Space was ocean and ships were... ships, so you needed ground units to actually seize the planets. Cost aside, I was always a little confused what the point of surface units is in this.
Which raises another query on whether fighters and bombers should count against the maintenance free limit of the fleet?