More code has been written since then, true, but what new OS research ideas have come about since 2000? I recommend reading Brinch Hansen's The Evolution of Operating Systems paper as a refresher.And systems research (meaning: operating systems research) died somewhere around 99 or 2000, according to Rob Pike. Strange that he is still employed as a systems researcher, now 25 years later.
It all seems more of the same piled on top of more and more complexity.
PS: I suspect cy@ was being sarcastic.