It's a bit of all that I think gents. I too was surprised by their omission.

My understanding of their purpose was both of your explanations to be honest.

In a water crossing they will help maintain that 7nder bonnet bubble and encourage a bow wave. I certainly saw a significant loss of bow wave when I fitted a Bonner scoop to the GQ. It was crazy!! No bonnet scoop ans these inflate will provide some pressure to help stop the entire engine bay filling with water I'd you keep that bow wave out front.

I assume these have been left out to contribute to cooling especially in low speed.

I was a little surprised at how much sand got up into thr engine bay of the 62 after this last trip. I did do close to 800kms or so on the beach though lol.

It would be pretty basic to cut some out Plas. Get a set of plugs off ebay and they will look factory fitted.