Should corporate management involve juniors to express their views and opinion ? where is the line drawn ?

Line?  What line?

Junior staff are the ones who actually do the work.  They always know more about what's going on than senior staff do. 

The purpose of middle management (which is most of management) is to communicate information between the big decision makers and those who do the work, in both directions.  Therefore any manager who is not an expert on the view and opinions of their junior staff is incompetent. 

The management may or may not agree with the views of the junior staff.