I grow on a slight incline, so my raised beds are terraced. It's much easier on me and my back doing it in a raised bed than directly on a hillside. Plus all the reasons mentioned above. I do have better drainage and warmer soil in the raised beds. My father-in-law's garden not far from me, is usually a bit behind mine and less productive, and he grows in the ground. Of course there are also many other variables as to why that is so, but he thinks it's my raised beds that's the difference. I think it has something to do with it, but also maybe something else.
Jen