I have a 2011 Legacy and I just wondered what that bottom part of the grille is, it recesses deep into the car and leaves often are caught back in there, against a metal mesh-looking thing.  Whenever I am washing the car I always wonder if it's dangerous to get too much water back in there.  I never spray water from the hose into that area, but I just want to know if water getting back in there would be harmful.  Tonight when I drove home from work a storm hit and it was pouring rain and the street by my house had water deep enough that there was spray coming off my tires about 3 feet high (that's how high the spray was flying up).  The car had no problems mechanically from that but it still worried me, I couldn't tell how deep the water on the road actually was.  It wouldn't have to be too terribly deep to get into that area on my grille.

The lower grille area is actually the main entry way for fresh air to get to the radiator.

The engine doesn't draw any air in through that opening, so getting water there isn't going to hurt anything, but you should try to keep it free of leaves and other debris. (like raccoons and birds)

 

I say that jokingly, but I have had to scrape critter guts out of the lower grille of my car on several occasions.