1. Academia has fallen into a self consuming game where fierce individual competition to appear productive means that researchers don't have the space to actually think creatively and come up with incredible new insights.
2. Scientists like Higgs had the privilege of lower hanging fruit to harvest in their day, so a career of lesser intensity was sufficient for people in his cohort to produce incredible contributions. Modern scientists legitimately have to work harder to produce less profound results.
Maybe there's something to both lines of thinking.
I'm also reminded of the classic story of the pottery teacher who graded one class by final project quality and another by total weight produced over the class period, and found that the latter group ended up producing higher quality work. Higgs in this article seems to be of the persuasion that in his profession, the former style produces better results. I think many of us here would find that intuitively wrong in general.