I have absolutely NO problem cooking with campfires or hearths. I place 4 racks across the small hearth, evenly spaced where the "front" legs are as far forward as possible. Yes, the racks are OVER the fire. That way when I stand in FRONT of it while cooking, the food comes right off the racks and into my inventory. If your hearth's edges are well above the surrounding ground level, put steps where you plan to stand so you don't have to jump up ON the hearth to get close enough to get your food, but not get burned. I have been burned ONCE when I first started playing.

Yes the sound is there to let the player KNOW that they are being damaged by fire. If it wasn't that way in the beginning, it's probably because someone whined about dying while cooking food and couldn't figure out why.