The major point that I've discovered from doing this stuff for years (on considerably more complex cases than the example above) is that programming efficiently for a modern architecture is qualitatively different ...

I think this is a great point. Low-level programming has always required an in-depth understanding of the underlying hardware and that hardware is changing as fast as ever today. It may be true that a large percentage of development can live happily in a land of high-level abstractions, but there will always be a need for low-level optimization and that space is still rapidly changing in very interesting ways.