My sister does it to get rid of her vegetable scraps. She doesn't have much growing/non-paved land, and she and her family eat a lot of vegetables and fruits. Her weather is never freezing, but sometimes in the summer it's too hot for the worms. I don't know what she'll do in the summer.

I've got a fair amount of growing land with a serious deficiency of nitrogen. I also have a ton of leaves and other wood debris. So I do a whole heap compost. I get a few worms, but lots and lots of wood lice (potato bugs/rollie pollies) and centipedes. I obviously need to eat more fruits and vegetables to help with the nitrogen content. (It would also help if I drank coffee for the coffee grounds.) Oh well, I figure I am in the process for the long haul.