Being barefoot isn't uncommon outside the West -- so, the connotations/norms around it aren't at all universal but specific to a certain Western understanding (or a relevant non-Western culture in question).

Some nascent research on the benefits of going barefoot --
- a simple summary from WaPo

- A couple of the studies the WaPo article seems to be referencing (can't vouch though for the kosher-ness of the journals or the authors) --
Earthing (grounding) the human body reduces blood viscosity-a major factor in cardiovascular disease. - PubMed - NCBI

Earthing: Health Implications of Reconnecting the Human Body to the Earth's Surface Electrons

Can electrons act as antioxidants? A review and commentary. - PubMed - NCBI

And, some research on barefoot running (or just running as most of the rest of the non-Western world would call it!) --
Working memory is better after a barefoot run -- ScienceDaily
and
http://barefootrunning.fas.harvard.edu/