Thought provoking to say the least. I would argue however that the examples cited all have a certain assigned explanation (humor, dread, sadness) which do point to the fact that even this nonsense does need to have a certain impact (perhaps not intended by the developer, but an impact nonetheless) on the player.
Which yeah, that might sound redundant, but what I mean is that "pure nonsense", which simply confuses everyone and doesn't evoke any other emotion or theme, perhaps is not an interesting place to explore. As you yourself said, excessive nonsense makes the player numb to the whole thing. I wouldn't say that the developer needs to have a rational explanation behind everything in the game, but I do think that they need to have a purpose. Maybe the purpose is simply aesthetic/emotional, as in "I think it's more impactful that way" or "I just found it funny", but it's still a reason to do it.
I guess what I'm saying is that I'm not really sure what you mean by "nonsense". Your examples may not make "logical" sense, but they still make "artistic" sense - you've identified an emotion that resonated with you, and the nonsense cited contributes to that experience. It's a piece of the puzzle, an ingredient of the cake, the product of an artist's mind, like any other.
If you suddenly discovered that what you saw was entirely generated by IA, and as such, the nonsense you saw was just the result of a glitch in the system, would you view it with the same eyes? I'm personally in the camp that the player's experience is all that matters, not the process behind it, and even I would feel at least a bit disappointed by that. I guess I still need to know that what I'm seeing is intentional. "Pure nonsense", as in someone just randomly putting stuff in, may be impactful or enjoyable, but it will never resonate with me as strongly as feeling connected with another human through a game.