I just dipped into Appendix F for an unrelated reason, and I think it’s funny that out of everything Sauron ever did — a master craftsman and teacher, a commander and conqueror, a deceiver and seducer, who achieved so much and, even in defeat, usually came verrrry close and tended just to reappear later all the stronger — one thing he utterly failed at was making Black Speech the common language of all his servants. He made grammar and vocab and syntax, and then the orcs could never figure out how to use his system. They ended up with such a hodge podge of fragmented, bastardized versions of the language that they were often incomprehensible to each other and had to fall back on Westron, the language of their enemies, to be understood even within Mordor.
It feels extremely JRR to me that he would let his Big Bad Villain kill and maim and enslave and despoil the environment, but he simply couldn’t allow Sauron to succeed at…linguistics.
