What makes the Coen Brothers’ dialogue so unique?

I've been on a Coen Brothers kick and I love their dialogue, trying to figure out what makes it so special.

No Country for Old Men: What's the most you ever lost on a coin toss?

The Big Lebowski: He peed on my fucking rug

Fargo: Blood has been shed

A Serious Man: Living arrangements

Two things come to mind:

1) Ten-dollar words. Little flashes of bigger vocabulary in the middle of a conversational sentence.

• "Also, Dude, 'chinaman' is not the preferred nomenclature."

• "Things have changed. Circumstances, Jerry. Beyond the, uh, acts of God, force majeure."

2) Existential dread and hopelessness. Coen dialogue has this feeling of: There are larger cosmic forces at play that we people are helpless to understand or influence, as we scramble and scheme to survive. The Coen Brothers universe is uncaring/antagonistic and you can't stop what's coming.

• "You know how this is going to turn out, don't you? I think you do. So this is what I'll offer – you bring me the money and I'll let her go. Otherwise she's accountable, same as you. That's the best deal you're gonna get. I won't tell you you can save yourself, because you can't."

• "I gotta tell you, the life of the mind… There's no roadmap for that territory… And exploring it can be painful."

• "The Uncertainty Principle. It proves we can't ever really know… what's going on. So it shouldn't bother you. Not being able to figure anything out. Although you will be responsible for this on the mid-term."