Currently, when adding a new section to a user or article talk page, the section header automatically becomes the Edit Summary, and there is no option to change that.
Section headers are usually not as long as a good edit summary, nor should they be. The current system contributes to the false belief that a section header is a good enough edit summary. This is seen every minute on Wikipedia -- when people edit a section, the default edit summary that is filled in is usually left alone, leaving other editors to wonder what was changed in that section and why.
I propose that an optional Edit Summary field be placed below the section header. If text is entered there, then that is the edit summary. If not, then the section header will be the edit summary as it is now.