> The majority of the cost, even today, are not related to rockets.
"Even today". There is an opinion that payloads are so expensive because the launchers are expensive. I.e., you can't send replacements easily, because a launch is expensive, so you have to design the payload so that it wouldn't break, and last 9-s of reliability cost additional 0-s in price.
In other words, if launchers would become cheaper, that would encourage sending more payloads which isn't designed to be as reliable and serve as long. If something happens, just send a replacement. The issue of space junk comes to mind, but if launches are cheaper you can include into the launched mass the active means of dealing with space junk, like fuel for deorbiting.