OK, I followed the links to Nikoli :
http://www.nikoli.co.jp/puzzles/1/hand_made_sudoku-e.htmI don't understand their argument so well.
They give an example, which they think is a "bad" sudoku,
but they don't give an example of a "good" sudoku.
The bad thing could be, that the first step were too difficult,
while the following steps were too easy ?
That would be pretty easy to avoid by computer too.
Indeed, once you know, what you would consider a good sudoku
you should be able to implement it.
Their statement, that computers will never be able
to make good sudokus like they do reminds me
a lot to the laughing at those early chess-computers,
which had no positional understanding etc.
To me it's clear that the days of handmade sudokus are numbered.
Their might indeed actually be some differences,
the Simonis paper
http://www.icparc.ic.ac.uk/~hs/sudoku.pdfseems to show that the handmade are
i.e. harder to solve with "forward checking plus shaving".
Although I don't know whether a human can recognize this.