No one's saying the image improvement is fictitious. We acknowledged that it isn't, from DVD to Blu-ray. It's still badly lit and colour timed on a basic filmmaking level, any student would be ashamed of.
It's not dark and moody, it's just badly done and passed off as that. Alien is dark and moody, Covenant's dark and moody, Under The Skin's dark and moody, IWA Vampire's dark and moody- none of them are badly lit, or have severely f**ked up Blu-ray masters.