Jazzak Allah hul Khair.
This is the only hadees which is quoted for this purpose. People did not commit any other crime and came and confessed ? In all of the big population of Arab there was only one Muslima/Ghamdia who needed to be purified that too with such a severe punishment. People did not commit any other crimes in those days for which there are punishments specified in Quran e.g theft , murder . usurpation of rights and wealth of others and then came and confessed to be purified ? I find it very disturbing. Quran does not specify Rajam ( death by stoning) as the punishment for zina and based on this hadees we are adamant to kill those who commit zina and ignore Quran in this case. Hadees and sunnat cannot supersede or override Quran but we are exactly doing that, it is very very disturbing for me. May Allah give me some guidance and wisdom to understand the wisdom of this hadees and other ahadees which override Quran. Ameen.
The punishment of Rajm, in a real islamic society, could go in favor of the criminal. If a person reverts back from his/her confession, even during the process of stoning, judge has to stop the punishment ..
no other system offers that leverage to the criminal ..
when confession is given so much importance, right of denial is also given to the accused, in Islam.