I change my oil 5-6 times during the year. Doing it myself is no problem but there are times that I just don't feel like spinning a wrench and had there been a easy and affordable option I would have taken it. I spend about $20 on Motul and filter so if there was a place that I could ride to, sit down and have a smoke and a cup of coffee while someone else got their fingers oily, then an extra $20 is worth the convenience. If that shop existed they'd get my business a couple times a year. Oh, the added bonus is I wouldn't have to deal with taking the waste oil to the recycler.
I agree with the posters who say that convenience and price are the major selling points. A range of service, as previously mentioned, is a good way to cover the different rider types i.e. Basic Change:$35 - Full Maintenance Oil & Lube:$$?(cost depending on range of service. Brakes, forks,wheels,etc..).