Where Mindustry falls short for me is where once the waves are over, you're forced to leave your base and start all over.
I'm not motivated to invest in optimization if the production line is going to be abandoned soon; the game becomes more of a tower defense, and less of a production one.
Play custom game, survival mode and see how many waves you can survive. I think the campaign is more of a tutorial thing and to have a mode with a sense of progression.
Have you tried multiplayer? I think it would make optimization more important, as I agree in single player it's a bit too easy to cheat the system with sloppy production lines by just adding hella barricades and getting the best guns.
I'm not motivated to invest in optimization if the production line is going to be abandoned soon; the game becomes more of a tower defense, and less of a production one.