I see, it will, but should I be concerned about how much "work Calibre is doing

really?
Yours is obviously the most elegant and correct way to do that - but its a usability thing, I know how to edit metadata, and I know where that swap author title box is.
If I had to go into preferences then import/export and mess around with saving regex expressions... I mean, I just wouldn't
Most people don't learn everything about every program they use, so are most likely to use the most easy accessible simple option to do what they want.
I know its wrong and I know its dirty....