You have the right to your opinion. I, however, have seen more than enough maggot-infested ulcerated mammary tumors, 10 pound pus-filled uteri and unwanted puppies left to die in a plastic bag by the side of the road to make me quite adamant at trying to convince as many pet owners as possible to spay and neuter their pets as soon as medically advisable. I've heard it innumerable times from the owners of pets that have suffered with the above mentioned conditions, and who have died as a result of those conditions, how they had wished that someone had beat it into their heads to have their pet spayed or neutered.
Oh, and for those that think only intact females can have medical issues and that their male dogs will be just fine, last week, we diagnosed a 7 yr old Boxer mix with a huge tumor in it's abdomen. We did an abdominal exploratory because X-rays could not tell us where the tumor was coming from. We did find out...it was a retained testicle that had not moved into the scrotum. It turned cancerous, a common occurrence in cryptorchids, but was inoperable by this point as the tumor was well attached to the dorsal wall of the abdominal cavity as well as growing through the pelvic opening. The dog has only a few weeks left to live. And just yesterday, an 8 yr old Labrador was seen because he had blood in his urine. Well, the blood is coming from his prostate, which is about 4 times the normal size, and if the dog survives being neutered to remove the source of the testosterone, the major contributing factor to enlarged prostates, and the biopsy reveals the prostate to also be cancerous, a common finding, the dog will have to undergo chemotherapy if their owner can afford it, or again, face a very limited future life expectancy.