Idea Summary
Right now, when you export data using APEX_DATA_EXPORT there's no way to exclude headings and if you send null the column names are used as the heading.

Use Case
This is useful for data exchange where the party inserting the data does not have the option to exclude the heading row/first row. This way you can data interchange without any kind of manual intervention.

Preferred Solution (Optional)
I would say a new parameter p_exclude_headings boolean default false, in the export function of the APEX_DATA_EXPORT. This way you can have the default value continue working as it is and if you don't want the headings, you pass true to the new parameter.