There's a lot of positing here. To assume the "average user" doesn't understand what browser tabs, PDFs, and FAQs are seems ... odd. Now these may or may not be fine tips, but they are not recommendations based on best practices or any research that I can tell. If they are, I'd be interested in seeing it.
Every major UI change has a backlash. Many corporations and businesses are still on XP because the change for Vista/7 was too great and required too much new hardware for too little benefit.
Quick thing on Terminal. I noticed that I had to limit the scroll back history in Terminal or else it eats up all your everything. For example if you have a number of term windows open and they are tailing log files or have verbose running processes open. I put it at 10k or so and things are fine now.
It says "Modern experience for modern browsers and devices.". Is that just an empty sentence or are they using a better engine? The paragraph after just talks about pixels and white space.
http://en.wikipedia.org/wiki/Evelyn_Beatrice_Hall