I agree with the general thrust, but ... even though modern western society does scorn plumbers (compared to philosophers), our pipes do hold water, and I don't have any complaints about the overall quality of plumbing.

Our society may not have much high words of praise for excellence in plumbing (you're more likely to talk about your hobby as a wildlife photographer than your job fixing toilets on your OK Cupid profile, even if you're average at the first and excellent at the second), but good plumbers get more money than bad plumbers, which is enough to get quality plumbing. By contrast, good philosophers get more praise from their peers than bad philosophers do, which is both harder to evaluate and less motivating.

So I don't think it's a matter of humble activity / exalted activity; designing bridges and transplanting hearts are exalted activities too, and we don't tolerate much shoddiness there.