Why 432hz Tuning?

That is why I call it relative pitch.

@antigrunge2. 
“If the instruments had been tuned to 432hz, the resulting overtones would have been part of the recording. Simply electronically transposing the recording cannot reproduce something that isn’t there.”
Thank you for this great point.  
You are correct in the inherent silliness of electronically changing the pitch of a recording after the fact.  
“Ooooo, now we can listen at 432, honey!”  
🤣🤣🤣

Seeking out recordings that were actually recorded in 432, okay.  
Now we have something here.

I suspect that convenience, not wanting to change from the norm, and a sense that the 432 argument is “just woo woo gibberish” has kept us from adopting 432 as the norm.  
Based on the evidence, I don’t see why we wouldn’t just make 432 the standard.  
It seems to be what we like more.

Are we sure that the algorithm used to adjust tuning to 432 Hz doesn’t also change the overtones? The study cited by the OP was double blind and used music that was recorded at 440 and adjusted to 432.

The study showed measurable physical differences for 432 tuning that we usually associate with relaxation as well as reported increased enjoyment of the music:

The subjects were more focused about listening to music and more generally satisfied after the sessions in which they listened to 432 Hz tuned music.

One study doesn’t prove anything but to say that 432 Hz tuning is nonsense when you don’t have any proof isn’t very convincing either. An open mind is a good thing.

Lots of Folk/Old Time fiddle music is played on a fiddle that is either "Cross-Tuned" (AEAE, GDGD etc.) or "Black Mountain-tuned", cross-tuned but with the high E string further tuned down so it is a Third above the A string. These alternate tunings certainly limit the instrument’s flexibility to play in different keys, but they convey a wonderfully folky/primitive flavor and easily allow for magical harmonies and unisons. In other words, a whole world of music opens up when you stop obsessing on perfectly 440 pitched music ensembles. Let a thousand flowers bloom.

I guess my whole point in posting this is the fact that 432hz connects us to the universe. It seems like the most natural tuning. I feel as a species we are losing our ability to be part of the whole. But you have to watch the video to understand that.