People are drawn to gas logs as a heat source over burning wood or other solid fuel because of its convenience and cleanliness. 
Although gas logs are certainly less labor intensive and require less on your end as a homeowner (no stoking the fire, no gathering/hauling/splitting wood), there is some maintenance required for gas logs, and most major manufacturers require this in their literature to maintain a warranty. It is absolutely necessary to have your gas logs serviced.
Not only is it required, it is also beneficial to you as a homeowner with bills to pay. There are spiders, dust, cobwebs, and countless other small particles floating about your home, in your carpet, etc. which can enter the orifices of your gas log set and cause it to burn inefficiently. As a safety note, the gaskets in a gas log set have the potential to wear over time, which, left unchecked, could cause a very dangerous carbon monoxide situation in your home. A certified gas log technician will come out to check these things and clean the logs. The peace of mind combined with keeping your warranty is certainly worth the fee.
When a technician comes out to your home he will essentially make sure that the gas logs are working properly, are able to burn at maximum efficiency (which saves you money), and ensure that all of the parts are functioning properly and appear safe. He will clean the logs and the burner and clean all the orifices in the set after vacuuming the entire firebox. He will check to make sure all of the safety features are working properly and the switches are checked. He also assembles the logs back together according to manufacturer specifications. Gas logs function best when positioned exactly as the manufacturer recommends.
After a cleaning of the control area as well, the technician will light the gas logs and monitor it for a period of time to check flame height, color, and generally make sure that the lit gas logs are behaving in an safe and appropriate manner. If any adjustments in flame height are needed he will make them. Your technician may instruct you to spray gas log cleaner on your logs as needed. Having your gas logs serviced is a necessary part of burning gas logs and is the responsible thing to do, especially due to potential health risks that can be caused by inefficient or malfunctioning gas log sets.