The Nebulas have a single static image because we only have a single, static image and the game isn't programmed to use a random colour. I have asked Mike about making other changes to the Nebulas before now though and he hasn't replied about them, so it might be worth reminding him of those ideas as well as passing on your idea. I'll send him a PM.
...The other ideas included multi-sector Nebulas if you were wondering.

_________________"Anyone without a sense of humour is truly at the mercy of the rest of us."

