Well, it's either a pill, or moving out of the city, or a fecal transplant (assuming that the urban / rural divide is relevant, and not just a proxy for diet).
I don't live in the city, but if I were told that I would be healthier with more of these microbes that my environment doesn't support, I'd opt for the pill.
However there is an obseity epidemic and a depression epidemic, and its plausible they are related. Which doesn't mean they are, but seems like something worth looking into.
The study compares humans (who happen to live in cities) to primates (who definitely don't live in cities). It doesn't compare between human populations.
I don't live in the city, but if I were told that I would be healthier with more of these microbes that my environment doesn't support, I'd opt for the pill.