Personally I think too many people rely on their yard as an exercise tool. I think a yard is a good place for a dog to potty, play fetch, and perhaps a place for the dog to spend some time on a nice day when you are cleaning the house or something, but it isn't a yard that defines a person's ability to properly exercise their dog. There are plenty of good ways to keep a dog fit while making it more interesting (not the same old yard day in and day out). I think if I relied on my yard as my dogs' main way to burn off some energy, they would become bored. An onleash hike, in my opinion, is more stimulating to a dog than a game of fetch in it's own backyard.

I would rather adopt out to a sporting home without a backyard than to a pet home with a big backyard.