We're obviously no longer in those times. Many things that were once sustainable are no longer so. It is well understood that cotton production will face considerable difficulties in the future. At the same time the demand for cotton has exploded along with global population. Consumer prices of cotton do not accurately reflect the production cost due to the usual reasons (externalities, lack of global water pricing mechanisms).
> Water is a very inexpensive resource in most parts of the world.
I don't think you know what you're talking about, and you're (like myself) living in a privileged part of the world if water is an inexpensive resource to you. Freshwater scarcity is going to be one of the most critical issues exacerbated by the climate change, and as I said, particularly so in those parts of the world where cotton is grown such as South Asia. The most famous case of cotton production having catastrophic consequences is the Aral Sea (https://en.wikipedia.org/wiki/Aral_Sea).