Money is an essential feature of civilization. As the 'trade' system in SE IV currently works you have to scrounge around for things that your trading partner might want. And if you can't find something in your possession that the party with the goods
you want is interested in, you're stuck. It's like being a primitive tribal trader with nothing but raw goods to offer.
The 'technology' called
money was invented many thousands of years ago to solve this problem, and there's no good reason to assume that advanced space-faring races, even very alien races, couldn't think of the same solution to the trade problem that our relatively crude and unsophisticated ancestors did. There really does need to be some sort of
money in the SE universe. It doesn't require fancy accounting or banking systems. We can 'aasume' that just like we assume the trade routes and freighters moving our resources. But yes,
money is essential for dealing between nations and empires just as it is between individuals. Even today the US Government pays
money to other governments for various purposes, and also receives
money from other governments.
On ship construction, I certainly agree that the SE III system where 'blank' ships appeared when purchased and were slowly 'repaired' to operational status was better than the SE IV 'instant ship' system.
I hope something like the SE III construction method is restored in SE V.