You may sometimes see airboxes described as "still air boxes" and AFAIK one of the original design objectives was to provide a relatively still (as opposed to turbulent) pool of air for the induction process. Airboxes (at least, some airboxes) then developed the additional benefit of ram air whereby the air pressure inside the box became higher than ambient pressure - passive turbocharging.
My experience is less in cars than in motorbikes where very significant increases in power come from a well designed airbox with properly placed and shaped intakes.
On the contrary, I've seen quite a few bikes where owners have removed the airbox in favour of pod filters and the results have been tragic - almost invariably a loss of peak power, very poor throttle response and inconsistent fuelling.
The engine bay of a motorbike is a rather different place to that of a car, particularly as car engine bays are increasingly shrouded so I could accept that the whole engine bay is becoming in effect a giant still air box and maybe even a giant ram air box.
But I would be fairly cautious about removing what the manufacturers have put so much technology into building.
Regards
Bryan