Par ID and purpose?

[MeTo]

My truck started taking on water above the PCM. The seam sealant underneath the cowl, between the firewall and cab had deteriorated and cracked. When cleaning and prepping the seam; I noticed debris trapped below where the water runs down behind the fender liner. Their is a rectangle rubber restricter that appears to only allow water to flow down, but traps everything else. We live in the woods, so their was about 6" of crap in their. I removed them and flushed the cavity clean. What are they for? Do they need to be put back in? I would like to leave them out. They would need to be cleaned once a year and the cowl would need to be removed first, PITA.