Interestingly, orange/red are just the colors that happened to be the base of most canon missions in Antares. That's the only reason orange is a staple of BtA's palette.
Much of the design came from a similar problem that I remember HerraTohtori talking about for WiH's backgrounds. How do you take a campaign that takes place almost entirely in one system and make a background that does not get tedious and boring by the end of it? I'll wait for final judgement after our full release, but my solution was to create a nebula design that is unique enough to almost be able to recognize which way your are facing based on what part of the nebula is visible or not visible. I included several large unique 'streaks' and a few different styles. Then I used some Post Processing to help blend the background and scene together into an almost faded look since the story is takes place pre-FS2.
That was my thought process anyway.. dunno how much of that made it through or if it just happens to look nice.