James Fallows has a post triggered by the Republican debate, when Wolf Blitzer led off saying "Wolf" was his real name, then Willard Mitt Romney followed claiming "Mitt" was his real name. The discussion touches on the difficulty with modern databases, which usually force people into the WASP naming, pattern: first, middle, last name, with no tolerance for someone who wants to be known as "Mitt Romney", much less someone from a different heritage (Hispanic, Arab, Russian, whatever).
In that context I'd like to tip my hat to a long ago designer of ASCS data files, who included both the separate name fields, plus the 33 character, if I recall, name field, which at least for a time permitted us to accommodate Mitt Romney and to record his full legal name (or Bill Clinton and William Jefferson Clinton).
On the other hand, the structure might have been simply a historical accident. In the 60's county offices were sending an 80 character record (for the punch card) to Kansas City, which I believe included the 33 character name field. When it came time to design the master name and address record in the early 80s for use on the System/36, they added the separate name fields, one advantage of which is the ability to search and sort by last name.
So that's two alternative stories: at this point I don't know which is right.