Instead of columns being equally distributed in a PDF export, allow the user to define the width as a percentage of the page. Today, if you had two columns, the PDF export automatically creates 50% and 50%. Provide the user the ability to set a width for each, such as 20% and 80%.
This allows a tech writer to create tables that do not inappropriately use the real-estate and seem odd to the reader. For example, the first column is an image or a label and the second column a description. There is no reason, and it appears odd, when the first column is half the width of the table.