My impression is that it all started much earlier. The old Apple (classic Mac OS) had very strong interface design culture and it continued into early releases

My impression is that it all started much earlier. The old Apple (classic Mac OS) had very strong interface design culture and it continued into early releases of Mac OS X, but the decline began to feel in v10.6, I think, if not earlier. Take, for example, the new search interface, where you first type a query, wait a little while it's hitting the search index, and only then get shown a button to choose the search options. Compare it with the old search utility (from the classic Mac OS) where you have both ways (simple and advanced) right from the start. The new way was already a crime unimaginable in classic Mac OS. Yet it happened, and I've just checked it -- it was in v10.4 in 2005. Cultures die slowly, so the wrong turn has probably happened much earlier than the author thinks.