There are many people who rightly believe that a dog needs all of it's available hormones to mature correctly, both physically and mentally - I don't disagree when I imagine pre-pubescent teens being neutered or spayed and the consequences that would bring about i.e. think castrata opera, girls having no breasts and I wonder what it does to their minds maturity wise.
The cancer of a hidden internal teste comes about as a result of internal body heat and what that does to the teste's cells. During my lifetime spent with horses, I encountered many senior "crypt orchid" horses and they were fine.
I had all of mine fixed early, but given my time over, I not sure I would do that again, especially if I only had one dog or more than one of the same sex.