Thanks to P. Batard (Author of Rufus):
It came out that the new Windows 10 doesn't ship anymore with a diskcopy.dll containing the ME floppy boot disk (please read as MS-DOS 8.00).
Of course the floppy image can be extracted from *any* OS (XP to 8.1) and although there is still the possibility of using FreeDos or one of the other "alternative" DOSes freely available, it would be nice to provide an easy way to get the file (that is not redistributable) though obviously the internet is full of "DOS boot floppies" (which may however be of dubious origins).
Any idea of the whereabouts of a "legal" downloadable file(s) (i.e. hosted on MS servers) would be appreciated.