Chalking everything missing from go up to "the designers know what they are doing--every omission was on purpose", ignores the way humans design things. We are really good at post hoc rationalization.
Bob: "Why did you draw the woman in tall grass?"
Alice: "To allow the viewer to engage with the piece by forcing them to use their imagination to visualize the hidden area."
Bob: "Are you sure it's not because you don't like drawing hands and feet?"