There are several reasons why people turn to raised beds. 1. Working with the native soils. A perfect soil is a perfect combination of clay, sand and organic material. this perfect soil exists in nature in very few places. most often soil is an uneven mix of clay, sand and organics, in many cases you either have mostly clay with little to no sand and some organic material, or you have mostly sand with little to no clay and some organic material. If you are a farmer you have the tools - tractors and what not, to amend large parcels of land, adding organic materials to perfect the soil. If you are a backyard gardener you do not have the tools nor do you want to pull in tones of material and using a shovel and wheel barrel to move, and mix that material into the soil - especially if you try to do it all in the first year. Raised beds allow for one to pick and choose small plots of land that they slowly amend. Clay soils do better with raised beds since plowing or digging and turning soil creates a 'bowl' of compacted soil filled with loose soil - this is not good if you add water - the roots of your plants are being left standing in a bowl of water. Raising the bed above the surrounding ground allows for more drainage. Sandy soils should be raised the first year, actually dug out about 2 spades deep and a thick layer of organic material laid in. Say bales of straw (not hay, hay has seeds) grass clippings, leaves - I personally stored up a year of newspapers, laying in whole sections thick creating a dense water catcher. since you are going through all of this work to create a stop for water to hold it close to the surface, you want to keep using that area until the organic material decomposes (taking 2-3 years depending on the material and how deep your bury it. Even perfect soil will need to be amended each year - usually in the form of spreading and hoeing or raking in composted material into the top layer of soil. Far easier to do in a loose soil, in narrow beds than in a field. 2. Planting, harvesting, weeding, mulching. Raised beds are usually around 3 feet wide - allowing ease access from a pathway on either side. One does not step in the bed, one just reaches in a hand or a tool to plant, harvest, pulls weeds, spread mulch, blah. If you step in the garden bed you are compacting the soil. Plants tend to do better in loose soils. the looser the soil remains over the growing season, the more roots the plant will put out, the deeper those roots will grow thus getting more food from the soil and utilizing available ground water more efficiently, lessening the amount of irrigation (watering) used. Once you create the bed and as long as you do not compact the soil then the post harvest plant pulling, the, weeding, the amending of soil is easier - you do not have to break through solid soil. 3. Succession and compact planting. Succession planting means to use the same plot of soil one season after another. For instance this year I grew peas in one plot - as soon as they were done I planted zucchini - actually I started the summer squash a wee bit earlier between the rows of peas. This is somewhat difficult to do with rototilling and other methods of planting. Raised beds make it a lot easier to do spot planting, spot crop changes, you can easily get at the spot of ground you want to work with. Compact planting means that you can greatly reduce the distance between most plants in a raised bed. The reason being is that you are concentrating soils (and organic material) and raised beds usually means you rely on trellises and poles and baskets - going vertical instead of horizontal - saving space. Compact planting also means less weeding. Thick patch of leaf lettuce shades out most weeds. a row of lettuce with room for walking, tools, etc tends to results in weeds between the rows. 4. Irrigation/watering Not only do raised beds lead to shedding of water of of clay soils, but they also can be formed with rims to hold water added in side the bed. In some instances 'flood' watering of the pathway - basically allowing water to flow between the beds is used. Drip irrigation, soaker hoses and other methods of direct or low water use is easier to use on/in raised beds than in other methods. 5. Sheet composting/clean pathing. In a Raised bed situation one can fill the paths with compostable mulches. I personally prefer straw bales. when the strings are cut bales tend to break apart in sections - basically squares of compacted vegetation. These can easily be laid down like paver brick, forming a solid path or patio even. Not only does this provide a mud free place to walk on, it also keeps most weeds from growing in the path (less weed pulling is always wonderful). It the bed they hold in moisture, reduce weeds. In the path the top layer remains fairly stable and the under dirt contact side degrades, rots and decomposes. By the end of the year I can rake back the top layer of now loose straw, finding a good layer of rich compost that can be scraped up and tossed directly into the bed - spreading out the old top layer of straw, and laying in new straw 'bricks'. Mud and dirt is something most people don't want to walk through to track into the house, having neat 'clean' paths not only keep the house clean, but also present a much neater/tidier look to the garden. I use raised beds for my veg. I have found it to be far easier and less work in the long run (although it can be a pain to set up at first), more efficient when it comes to energy and water put into it for the rewards coming out. It looks nice, takes up far less space and appears to produce more food than when we had the dog run as a 'field' that was rototilled.