So if an orbit brought an asteroid close enough to a star to have this effect on the surface of an asteroid, you would consider it an entirely different phenomenon?
The idea is that it puts Earth at the center of the biological universe.
Generally the idea is that abiogenesis is very rare. I don't think any panspermists are saying that it only happened in one spot. As you pointed out that's basically the same belief as thinking it happened just once on Earth. The two 'versions' (they're not mutually exclusive) I'm familiar with are spreading via waterbears on comets or whatever, and also seeding by intelligent life. I think we have evidence for both in our own solar system, although the life we've seeded probably didn't take hold for very long.
Sure, it's a tech demo. If you set the brightness on the demo to 7 early on and say "This is dark," you can then turn it down to 5 later and that will seem even darker. The idea is to start at 7, not at 5, because when you have to turn it down to 3 you can't see anything.
The Craster's fight and the wall fight were both at night and looked great. But maybe they should have been a bit brighter so there was more room for the narrative dimming and actually seeing things. This all feels like betting into an empty pot, though, because the darkness of episode 3 isn't even a top-10 season 8 complaint for me.