

In my version, I expanded on the idea of the demons that show up when you go astral or ethereal. They also come in after about a day to repair damage to the tomb and reset (most) traps. Resetting the traps is mostly a curiosity, since the players know how they work the second time. But they may actually run into the demons themselves who would not like to be disturbed in their work. That can add an element of danger and dissuade the players from wasting time. Of course they can just rest outside of the tomb, as long as they have actually found the way out.
I’m with you on the attrition. I think some of the other readings are overly literal or unnecessarily harsh.
The way I see it, there is actual writing on the floor tiles. It’s in small print so you need to be close and it will be widely spaced. If you want to read the whole thing, you have to move along the whole path quite closely, falling into a few pits along the way.
The kill chance of the needle traps is only that high on paper. If the players are that high level and not expecting poison needle traps on every lock, they have been playing a different game.
I don’t know how it is in 1e, but in B/X there is always a 1-on-6 chance of spotting a trap and there is some paragraph about a trap not triggering 50% (?) of the time. From what I read, nobody seems to use that m, but it’s in the rules. I think that might be appropriate in this case, because it gives a chance that someone in the back line (or multiple people) fall in the pit at once.