It would be nice to have a way of defending an outpost while you (or construction bots) build walls and turrets etc.
They would fly around the edge of roboport construction square and attack enemies. And they would take rockets or magazines as ammo (More intresting to automate = more fun)

Peaceful mode means that aliens are generated (for research and game progression) but they are not angered by pollution , only by attacking them. You can switch peaceful mode on/off using cheats

I'm assuming factorio is your favourite

You just don't have any bases in range of your pollution

The rocket launcher is not underpowered. It is useless.