This is exactly what the title says. If I can spend literally infinite money and resources that I don't have, and also literally duplicate turrets, why is there still a requirement for me to have system upgrades? At the very least, there should be an option for Creative by which that restriction can be turned off, and you can add as many turrets as you want.
It would make it so much easier, because you don't have to keep jumping around into sectors with Equipment Docks (which take at best 5-10 minutes to load due to stations, ships & asteroids) and buying out their entire stock.
I see no downside to this whatsoever, especially if it was made optional.