A table has a head row, which tells user the meaning of the column, like
Google file table has
But, in addition to presenting information in the table, I wanted the user to be able to perform some actions on the row objects: open the file for instance, or rename it, or make a copy of it. It is very convenient to do by simple click if you click one column, you open the file, if you click the name column, the name becomes editable, for instance, and so on. It is much more convenient than providing a menu button per every row, that needs to be opened with extra clicks.
Another option would be to add extra "action" columns to every row, the menu in the ready-unfolded form, which enables the single-click actions but takes a lot of space, failing the table to fit into the user screen.
That is why I tend to the dual use columns -- it displays some attribute of the row/object but does some unrelated action when clicked. How do you tell the user what is going to happen when he/she clicks the cell? Tooltips on mouse hover?