We (Commons) would like to have some text on the upload form that is hidden by default by CSS. (help information.)
If we include it in MediaWiki:Uploadtext, then for browsers that don't respect "display:none", it will be too overloaded. Therefore we would like Uploadfooter to appear last on the form, below the "Upload file" button. That way if browsers don't respect that it is hidden, it is still quite usable.
The default text should be blank.