I have problem when PDF document is stored at network drive and my notebook has temporary problem with WiFi. Or when notebook is suspended and later resumed, network drive is not accessible for some time (I have to reconnect it manually). In such cases I see many blank pages in PDF file that was opened in the past (new pages are not read from the file). I have to close document and open it again. That is not nice and I believe that "refresh/reload" function will fix this problem. It is possible to find similar requests in the forums on Internet.

Other use is for users who create their own PDF files, like printing to PDF file, so PDF file is changing on their drive.