One reason would be to keep rainwater from ever dropping off the cowl and onto the intake.
The 2004 and 2005 era Hemi powered Durangos have nasty problem of when they get some miles on them that water that gets dripped over the intake seeps past the intake port o-rings.
It ends up in a cylinder and hydraulic locks it and then spits one of the weak powder forged rods out the side of the block.

If you search google you'll find out just how common it is.

Anything in the way of an engine cover might help prevent it if it gets the dripping water out past the valve covers.

Dodge knew that had a problem with it and did a change/upgrade with the cowl sometime in about 2006.