> While the author acknowledges in the abstract that the internet has improved people's lives, I still see the tone implying we should all be directly working on more worthy causes if we really want to be doing stuff that "matters".
Er, no. Again, you are engaging in binary thinking not warranted by what was actually said. He doesn't say or imply "we should all" be doing any one thing, he very directly says that "society needs more people working directly on problems that matter."
Note, particularly "more people" (not "we...all" as you would present it), and "directly". That is, there are plenty of things that indirectly matter, and plenty of people working on those, but, in the author's view, not enough people working directly on certain important applications.
The judgement you are reading into it that everyone not working in certain preferred areas is doing something less-than-ideal and not doing stuff that matters is simply nowhere in the text.