What's the deal with ancient dangers?

[Call me Arty]

 Alright, some spacers got into some crypto-sarcophagi because their present situation was pretty hostile. I'm just trying to figure out the rest.

• They're bricked inside of them with no doors. Alright, maybe they didn't want anything getting in to tamper with them early, so they kept a couple bricks on the inside of it and Cask-of-Amontillado'd themselves. How'd they get inside of a mountain without leaving a tunnel? If it was a "natural" event, it still wouldn't make sense. A rock slide dropped solid rock everywhere except specifically on the ruins, and all of that rock is in one piece?
• Open the danger. There are some mechanoids and some artifacts. Alright, maybe this can make sense. These mechanoids imprisoned some humans (Experimentation? Study? So they could be released later to slay demons that came in through a portal to hell/ save Princess Zelda and kill Ganondorf?) and are standing guards, and they brought the artifacts to either control those humans when they came out, or in the case that two Scythers weren't enough for an army. Alright. Why are the Spacers armed? When it's the alternative, and it's a box full of (mega)spiders, why don't they just gnaw the boxes to pieces and/or escape?
• There's no infrastructure. Okay, it was an emergency multi-century freezing. They had to hurry to save themselves. There's no lights, power, machines, food, or tool benches for them to use upon escape. 

[Canute]

Did you ask yourself why you can mine compact mashinery or plasteel or why does that even exist ?
That planet is just old, and ancient civilisation exist long time before.
Even when you don't see a door, you can't say there was some in the past.
Do you know the mechanical wall's from a mod. What happen to these mechanical wall's when they arn't longer working, they are regular wall's.

Just keep your fantasy playing and find your own answers.
Ancient danger exist, create your own story about them. :-)

[MajorMonotone]

I actually quite like the idea of expanding the sarcophagi rooms into small bases built into the side of mountains, it'd make them much more interesting and could possibly provide refuge if you fend off whatever is inside.