Nice idea, but unfortunately kidney transplants are not that easy to come by.
There are the lucky ones of course who go on the donor register and get lucky with a cadaveric donor before they even need dialysis of any kind, but this does not happen all the time and some people can be on the waiting list for a long time before they get a good enough match.
Also, you cannot just pluck a live related donor out of the sky for someone. It just is not that simple. Firstly, they need to be related to you in some way to be able to get a good enough match. A kidney has to match blood type and be a good enough tissue type match, so that you do not get acute rejection whilst the patient is on the operating table.
Also, a live donor has to undergo thousands of tests beforehand to make sure that they are in a good enough state physically to be able to donate a kidney, to ensure that the match is good enough between donor and recepient and that there is nothing wrong with their other kidney, so that they will be able to live on just one kidney themselves.
Also, they need hours of counselling for all the psychological implications that a live donation carries. They will always have some kind of hold over another person, they are losing part of themselves and what their motives are for wanting to do it.
There are major ramifications, so donation is not easy.
Also, these days people can survive in a relatively healthy state on dialysis for a long time. Dialysis is by no means perfect, but if someone is well dialysed, they should feel quite well and be in a reasonable state to undergo a transplant surgery.
Anyway, as I said before, transplantation is a nice idea, but is not always an easy option. Lots of people have to wait years to get one, which is why so many try to get them on the black market and go to countries such as India to buy organs and this does happen. People in these countries will sell their organs for money and unfortunately, there are people around who are desperate enough to do this.