Dr. Bronner's was made long before the hippies latched onto it. It was first marketed as a Kosher product.
I don't buy it because it's Kosher. I buy it because it's one of the few soaps that doesn't make my skin break out.
Secondarily, it's useful for all kinds of other stuff.
I wouldn't recommend it for washing film but, if you're up for some science experiments, what the hell?