Because, as far as I know, the only way to access the 'extract all' option is first compress the file. Extraction can only be accomplished on a compressed file.
Thanks for the link! I'm going to try that out.

Not with an Office 2007+ file format. As I said before, these are already zip archives - they just have a different extension. So, if you wanted to access the 'extract all' option, all you need to do is to explicitly open the files with a program like WinZip or change the file extension to zip so that you can do the extraction. Compressing the files beforehand will mean the only thing you can extract is the xlsx archive as a single file - it won't give you access to that file's internal structure.

__________________
Cheers,
Paul Edstein
[Fmr MS MVP - Word]