I live in MN and my rabbits live outside all year around because of my allergies. My rabbits have a double dog kennel, 24ft X 14ft to play and graze in, complete with stools to lay under and cardboard tunnels to run through and they just love it. Although I have gotten a lot of bad comments from HRS members (who have no interest in checking out my set up), an animal behaviorist has looked at my set up and said that it is the perfect habitat for rabbits. I custom made their hutch, which is more like a cross between a hutch and a shed, 8ft long and 3 levels high which is mounted to a chain link fence for stability. My rabbit play outside, even in the winter and I don't think they would be happy in the house. Rabbits are not children even though many people like to think of them as such. They were born with the ability to adapt to weather changes for a reason and keeping them outside allows them to do the things rabbits love to do most. However, I do have to treat them with a flee preventative.
Judging from my experience, most people that are adament against putting rabbits outside are involved with rabbit rescue organization that rescue a large number of neglected hutch rabbits, and have no experience with caring outdoor rabbit owners!