I explained that. The passphrase can be longer, more complex, and actually changes the key.
A PIN is generally more truncated, only numeric, and doesn't change the key.
Humans generally have a better memory for language over numbers.
Both are entered as frequently, both can be obscured and backed up safely, and both can be coerced with a threat of violence. Having a duress wallet in either case is ineffective but much simpler to maintain in the passphrase instance as you can just NOT enter the passphrase to make duress transactions where as you would have to manually remove the passphrase in your scenario.
Again, I disagree with your assessment of Passphrase entry and HWW manufacturer incentives.