most of us are going to be big advocates of spaying and neutering at a young age to prevent more unwanted puppies
Although that's a good enough reason in itself, there is also the fact that irresponsible breeding is creating a cancer crisis in our pets. Currently for Boxers the most common of cancers are Lymphoma and Leukemia.

I would ask the original poster:

Do you know the cancer history of the grand-parents of your dog? For example did their siblings and all offspring from the siblings of the grand-parents yield no cancers in their lines? Most likely the breeder you obtained your dog from may not know the answer. Until steps are taken to limit ad hoc breeding, cancer in our pets will continue to increase in frequency. Will an individual owner consider that if the dog is a female, allowing it to become pregnant or allowing 2 heats to occur has increased its chances of getting mammary cancer later in life to be 25% compared with a spayed female never allowed to go into heat?

Then of course there are the other genetic diseases that some breeders are attempting to deal with in Boxers such as Subvalvular aortic stenosis which is sometimes difficult to detect initially, and leads to heart failure. There is an active program among breeders of Goldens to attempt to eliminate hip dyspasia. Will the individual owner concern themselves with the genetics of the breed when thinking about breeding?

Having already lost one dog to cancer, I avoid answering any questions concerning breeding health issues.