Thank you for putting software engineering into the soft skill bucket, but I think the word soft skill sort of means social/interpersonal skills. What you describe is more the difference between open and closed problems.
It is also a redundant definition, if you say that soft == social and hard == technical, then why not just say social and technical skills? However any experienced programmer knows that there is much more to programming than just knowing a language and frameworks, so to us it makes perfect sense to talk about soft technical skills even though a manager might think that we only have hard skills that can be jotted down as a list of checkboxes. So I think that breaking this misconception is very important, there are plenty of soft technical skills to care about when evaluating a hire!