The reasons why you want a raised bed are numerous. One of them is that it's portable. In other words you can move the garden from one place to another. If you plan on raising plants, that afternoon shade you can move them around to the east side of the house and get some afternoon shade. If you need a plant that needs some sun, you can move it out there and you're not stuck to planting the kind of plants that have to have the environment that is available where the garden is. A raised bed is an ideal situation for production of specialty items because of change of environment and to cater to the needs of the plant. Portability for a raised bed garden is anything that can be moved around a house plant that you have in your hallway that has a ficus tree in it, that is basically a raised garden. It's portable enough that you can move it outside when you need sun or move it in when it's going to be cold.