Do I really need this? What is it?

So my wife comes home a few days ago with this in her hand. Apparently she pulled up too far into a parking space and crunched it off on the parking block. There was another one hanging down under the front bumper which I went ahead and also removed. I can't really figure out what the purpose is. They seem to only bridge the gap between the underside of the bumper and the other plastic section behind it. The problem is I'm not certain how to reattach them since the little nubbie things (?) that hold it to the car have broken off. I certainly don't want to pay to have it reattached, especially if it's not vital.

It measures about 15"x 4.5" and there are 2 of them. Little help here?

 

<div class='quotetop'>QUOTE(Bill Merchant @ Jan 31 2007, 02:15 AM) [snapback]383193[/snapback]</div>

Thanks Bill. That makes some sense but my other concern is whether it might also contribute to keeping moisture and debris (and salt) form spraying and settling in the undercarriage, thus promoting rust. I'll likely try to reattach them sooner than later and take your advice and see if I can get some of those little plastic attachment thingies at a parts store.