Perhaps the main thing about tallow is that there's a glut of it, likewise lard. People want more and more meat, but want it to be leaner, creating a surplus of tallow. Also, its use in deep fryers, e.g., by the fast food industry, was curtailed when vegetable oil became preferable in the market.

A relative of mine worked in a chemical factory in Detroit, that made lubricants for metal working. Many of them were either formulated directly from tallow and lard, or were soaps. The materials were cheap, they worked, and were considered to be relatively non-toxic.

One thing I've noticed is that detergent based "soap" has disappeared from the market. It used to be that you could get detergent bars that contained no soap. They also didn't produce soap scum in hard water areas. Remember, "You're not really clean until you're Zestfully clean." Well, Zest was a detergent bar.

Today, looking for detergent "soap" at the store, it's gone. Even Zest is made from lard or tallow, last time I looked at the ingredients. I've banned soap from my house because I hate cleaning up the soap scum. We use liquid body wash instead.

/rant