What is the purpose of the black plastic that covers the radiator?

[bigborian]

On the bottom of the boxster there's a black plastic piece that is clipped onto the body of the car by plastic push in screws and it blocks the radiator/AC cooler. I'm assuming that it's there to keep excess dirt and all that other junk from getting up in there. However I don't do a lot of driving on dirt roads only paved roads and it's not very dusty or windy here in sunny California. Would it be beneficial to remove this plastic piece? All other cars don't usually have things block the radiator like that but for some reason the boxster does. It seems logical to me that removing this piece would improve the airflow and cooling power of the cars radiator therefore improving the cooling ability of the car. Any thoughts?

This is just something i was pondering please let me know if i'm wrong and why thanks.