The problem with usefulness (like with "impact", in my downvoted comment way towards the bottom) is that it is exceedingly hard to define. Where do you draw the line between "useful" and "useless"? Are languages useful? If so, to what end? And how do you teach them to not carry "useless" things while teaching? Are particle physics useful?
The other comment draws upon the distinction between vocational and educational, and what you see there is the same problem. What is considered "useful" for a given task or job, and what isn't? Usefulness is a very difficult category to define and abide, simply because different goals and aims render different areas useful or useless.
And we circle back around to the original linked document, in its spirit what a scientist would find useful is can it generate specific falsifiable predictions that can be tested and evaluated, if so, its useful. Particle physics is on the border and depends on some pretty esoteric lab experiments, and that border has been exceedingly fuzzy over the past century or two so don't be too drastic about setting that border in stone... On the other hand the point the article is making about non-scientists is usefulness is defined as, lets talk about it, now was that fun or politically applicable (or at least acceptable) or plain old interesting, well then its useful. The claim is given the core difference in philosophical outlook the two are not going to see eye to eye on much of anything, and at best a rebuttal is sometimes they might agree coincidentally or its not really as bad as he claimed, etc.
To a scientist a language is useful if you can make certain predictions about proto-indo-european and what you'd probably find if you dug up an ancient city over there, and it turns out when you dig up that city and examine the writing on pottery the writing looks like ... whereas to a non-scientist a language is useful if you can get students to attend a lecture and write a term paper about it, and if the conference discussions are fun and interesting.
As an outlook on life its about as useful as asking whats better, music or artworks?
The other comment draws upon the distinction between vocational and educational, and what you see there is the same problem. What is considered "useful" for a given task or job, and what isn't? Usefulness is a very difficult category to define and abide, simply because different goals and aims render different areas useful or useless.