+1, if you hunt and peck "data" files, I think you will find they are not massive (save for audio/video files potentially). The most common locations to "just copy" are C:\Program Data, C:\Users, and the Cakewalk directories with dynamic content (projects, etc.).
Robocopy
does have a longstanding bug in that it makes the target directory "hidden" upon completion which is truly a PITA to undo, but robocopy is required for a handful of situations which xcopy cannot handle (and the GUI is terrible). I prefer xcopy by far when it will "do the trick."
Another reason for the image/data file separation is the situation of "I want to do a fresh OS build but pull back in all of my data files afterwards." In this scenario, it is easiest to backup the data files "one last time," wipe the C: drive completely, and copy the data files back.
Interesting caveat if you use the desktop as a temporary repository and then move files on occasion to another "final home," is that a duplicate cleaner on the data archive may also be useful, but one which allows for protecting the "final home" path while selecting all other duplicates. This really depends on your file management schema, and unless you save audio/video or installation files, may or may not be applicable to you.