- They prevent lens flares in your picture (see above).
- They protect your lens from accidental bumps/scratches.
The way I get around not using a lens hood is I either move to change angles or I use my hand and hold it just above the lens (keep it out of view or crop out your hand later). Unfortunately, the latter means I'm shooting and holding the camera with only one hand. So, I'm limited to circumstances that give me high shutter speeds. But it works sometimes (see below).