There are basically three types of sheep, fiber sheep (for wool) dairy sheep (yes sheep are raised to produce milk) and meat sheep. We raised sheep, but just for wool. My wife and I can't raise any animal to be butchered, and we had a dairy goat farm, we didn't want to get into milking sheep as well. Milk have a very short lactation period, so milking them is not year round.
Some people have sheep for petting zoos, or they rent them out at Christmas for manger scenes, or they breed them for shows. I think sheep are super cute, but I wouldn't want to raise them. They're awfully stubborn.