Ok guys imagine this. The holes are small, Yes. The thing is, is your not getting any less air because of that. Now if you took the two mesh panels and crossed them, then you would be restricting your air flow. Because you would then be canceling each other out. Actually back in the day peple would actually make water tight sacks, by using that same technique. (Over lapping many layers of mesh like fabric) Ok enough of the history lesson.
What actually is happening is, the air flow is more controled, and entering with more force.( Ex.) Have you ever used a water hose? Ok when you turn on the water on and just let it run, it won't go that far, or the pressure isn't that great Right? Now what happens when you take your thumb, and place it over the end. Now you got yourself a pressure washer. Not only is it intensified, but because of the new pressure the air that is moving through the opening is going to be much cooler. Yup.. Thats why a lot inercoolers use the smaller mesh, or smaller tighter radiator coils. The mesh serves as function as well as look'en pretty cool. It even amazes me what controled air flow can do. Actually in my intakes I have mesh caps threw out the whole thing. I use them to make the air flow more controled, (directional) and less turbulent.
Thats why when you take your air box off you have mesh on both sides of the inport outport of the manifold. So I hope this helps clear up your questions you had. If you have any more always feel free to ask. I rather take five minutes and try to help, then to hear you blow up your car. Thanks