There would be a worse upheaval if you had uprooted your whole family from your original homeland, and then you had to take them all back again.
This is a big reason for the change in the rules. There had been several high publicity cases where a family had come to NZ with their JSV-holder parent, the children had made friends and had settled into school, and maybe the spouse had found a job - then it seemed very hard that they had to tear out all those new beginnings when the principle applicant couldn't get skilled work within the nine months.