I have owned Dremel tools for many years, and I currently own two of them. When I want to sand a project, I use a Grizzly G9928 Flex Shaft Grinder. This tool allows foot pedal control of the speed, and unlike the Dremel, you can sand at slow speeds with no issues.
So, what do I use the Dremels for? One is permanently mounted and used as a drill press, and the other is more or less permanently mounted in a router base.