If you are gardening in a dry area or just feel a dry garden season or maybe several seasons coming up using the "bent" bed approach for your garden beds make sense. I garden in Texas, San Antonio to be exact, and we have long periods of dry weather. While this could potentially stress the garden to no end using a "bent" or sloped bed can help ease this hardship.
Sloping the bed, and making a lip on the lower end ,will congregate the water at the bottom of the slope and keep it moister for a long period of time. Naturally, as you move up the slope varying degrees of moisture are present with the top being the driest. This method work nicely for all types of plants, but plants that require a moist soil have to have it in dry areas.
This method has been successful for me since I have moved to Texas. Even in the middle of drought periods the bottom of the slope will stay somewhat moist and give plants a chance to live.
Positioning a bed where the runoff from the roof of a house will keep water funneled to the bottom of the slope also. Even if its only a small amount of rain or water coming off the house from early morning dew this amount of moisture will help the garden as it will be guided to the bottom of the slope.
A bent bed approach will work in areas of very dry weather. Nothing can take the place of good old rain, but in the absence of sufficient precipitation one of the best things one can do is channel the water to the bottom of a slope where it can linger around for a bit to help your plants grow. Try it! You will be surprised at how much it helps.