What's the point of getting credits when you can build research or production directly? Converting credits to research or production is a huge waste of resources. And since maintenance costs are so low, it means as long as you generate enough credits to pay for maintenance, you don't need economic buildings.
Also, for some reason the synthetic AI generates a ton of credits. I've seen the Yor with 300,000 credits. Which btw is totally worthless because rushbuy is inefficient. What's with that?