Bunnies are not by nature aggressive but can develop the trait due to the frustration they feel by having to remain so long in such cramped quarters. Very similar to people forced to live in an 8 x 10 jail cell.
Not only does the ability to run and hop help give your pet a good disposition and a healthier life, but the opportunity to be outside and eat grass can also improve digestion and keep his bowel movements on a regular schedule. When you set up a run, do not place it on an area of the yard that has been treated with any chemicals or you can make the bunny sick. A rabbit hutch and run gives your pet a nice home where he can enjoy his days safe from the weather as well as predators.