This is a very good question. Unfortunately economics argues in favour of standardising everything and most consumers can’t be bothered with thinking about options, so effectively we all get pushed towards 175 for mountain biking, even though it doesn’t deal with the differences in peoples legs and it’s barely any different from what had been established for road biking. Cadence comfort is paramount for road, but much less so for mtb where you need short sharp bursts of power, so I suspect the difference is too little.
Clearly applications like singlespeed where power is most important need longer cranks, but by the same token I would argue that most women should use 180, and indeed men who find climbing a weakness should give it a try.