In particular, when the malpractice of the group has potential for causing significant harm. Without question, the activity of running programs on computers has enormous impact on society, both good and bad. As for the other two questions it is not clear that they have affirmative answers. The breadth of application of software is so huge that assigning the task of responsible design and construction of it to any one profession is meaningless. One might as well talk about mathematics engineers, or organizational engineers.
Software is just the latest reflection of a history of humans inventing and using processes.
In fact, I claim the whole purpose of software is to implement process. The fact that software is involved in the process is a distraction, the real issue is the role and quality of the process being implemented. Yes, there is a scale difference in that computers do more, do it faster, and so we can perform more complex processes. But this complexity is nothing new either - complex processes have been implemented in large bureaucracies for a period far longer than either engineering or computing science have existed. But architects design and construct buildings, chartered accountants and lawyers design and build company business processes, physicians design and implement processes for combating disease.