Why do you need handwriting if not to make people open the mail, who would have otherwise thrown it away?
And if they'd have thrown it away, how likely is it they'll change their mind after having been tricked into opening it because it appeared to have been sent by a human?
The point of junk mail is not to be read, it's to generate valuable/actionable leads; I don't see how handwriting helps -- maybe it does, but we would need to see ultimate conversion rates (not just rates of initial inquiries for example).
The point is to get people to open the letter, yes. Having people open the letter who won't actually respond has zero cost to the advertiser. The letter itself is a sunk cost, so trying to push people away from opening it is not beneficial. By trying to entice them to read, in the worst case, they just throw away your letter a little bit later. More people opening the letter is not a negative like being deluged with thousands of false leads would be for the Nigerian scammer.
And if they'd have thrown it away, how likely is it they'll change their mind after having been tricked into opening it because it appeared to have been sent by a human?
The point of junk mail is not to be read, it's to generate valuable/actionable leads; I don't see how handwriting helps -- maybe it does, but we would need to see ultimate conversion rates (not just rates of initial inquiries for example).