This is what he said -
The last update sparked a lot of discussion. I understand both sides, but since both arguments are very play-style specific (casual, hardcore, fighter, etc) it's not easy to make everyone equally happy. I'm trying to add more and more options for servers to find a setting their players can enjoy.
But as a game mechanic, buying blueprints from credits destroys any effort to make an economy. In game economies there are always "in"s and "out"s. You want to minimize the "in", else something like "demand" cannot be generated. Something that basically generates blocks from nothing is an infinite "in" which is ok for creative, but not ok in any other setting, since the "in" should be the blocks themselves (which are practically infinite already, but they take work to process)
Here is the source.
http://star-made.org/news/starmade-0-1851-hotfixes-and-more-mining
I will admit you never specifically asked for spawning blocks on the blueprint with credits, its just the easiest solution and the first thing that comes to mind.