There are many other animals that can outlive keepers; in the pet world, how about parrots? They often outlive their owners. Elephants in zoos outlive their keepers (sometimes these unethical people even retire); are you saying that they shouldn't be kept because of this?
I would side firmly with those who say as long as you plan for the animal's care after your demise (which should be done even with short-lived animals, and this has been covered in several threads already), than it is just fine. There is nothing that I can see that is unethical about having a ball python that might outlive you, or a tortoise that almost certainly will.
And, I personally don't think these animals form much of a bond with their owners. Perhaps my turtles will outlive me, but I think they'll bond just fine with whomever takes over feeding them!
It IS better for survival to have parental care and associated 'bonds'. That is how animals that do so can persist despite having only a few offspring (or even one) at a time. Animals which don't typically have dozens, hundreds, or even thousands of offspring at once. Obviously, these don't all survive; the odds are seriously against them.
Trevor, why won't you be keeping snakes when you're 60?