Why don't surgeons remove the diseased kidneys during a kidney transplant?

The only article that I could think of is that this would help yourself to more time that the patient would be lower than, possible hemmorrhage and increased chance for infection.Why don't surgeons remove the diseased kidneys during a kidney transplant?
A surgeon will solitary remove the kidney(s) during a transplant if the disease will spread to other organs or tissue, like cancer.
There are 3 prevalent reasons why they don't:
1. Longer time beneath anesthesia (the less time beneath anesthesia, the better).
2. More physical pain, tolerate alone the pain within the peritoneal cavity (the space where your "guts" are) where on earth they put the new kidney, but surrounded by the back where on earth the kidneys are located.
3. Longer recovery time. The body have to recover from primary surgery to put the new kidney surrounded by, and would also have to rest from from having kidneys taken out (the body have to "adjust" with the space disappeared where the kidney(s) are/were.
Pretty much, there's no rationale to do more than necessary.
They do if they inevitability replacing, but more than likely they will do them one at a time if one of them is still functional, this is incase the body rejects the transplant.
idea that they don't remove them is if they pose no health risk, than the removal would be a risk. simply that simple