The two main reasons to rely on an automotive expert to help you with oil maintenance are risk and convenience.
It is not as convenient to change your oil at home as you may believe. To begin you would need to educate yourself on the steps it takes to change the oil (and the oil filter) and then purchase the materials you need (correct oil, oil pan, filter, special wrench, etc.). After you have bought everything you need, you would then need to change the oil, clean up the mess, and bring the discarded oil to a place where it can be disposed of safely. At this point, you are most likely spending more money and time on it than you would if you had brought it into a shop. *Should you decide to change your oil on your own, please dispose of it properly at a hazardous waste recycling facility. These facilities can be located on Earth911.com.
When you have your oil changed professionally, the risk of something going wrong during the service -or with your car later on- decreases. Auto mechanics spend hours upon hours learning how to get the maintenance done properly the first time, every time. Meaning, that they are not apt to make rookie mistakes like untrained people could. Someone who is not properly versed in the functioning of vehicles runs the risk of using the wrong oil grade, improperly installing the filter, or overlooking a leak- all of which could cause expensive issues down the road.