It depend of area your stay and WHo stay around that area...
If have petrol cars rounting around, than you may not require to have Grill...example Lile PutraJaya without fencing but now more and more house installed Grill too
If you been target, even grill also cant help lol

if no grill, can replace with wire mesh/mosquito netting?  saw the home dec and newspaper got 1 company advertise. They say its a grill replacement. anyone tried it?