I understand.
However, I guess I was trying to show how there is no perfect solution. While some want total separation between them and the person in the other seat, others would not. It is not always strangers sitting next to each other.
It seems like having an armrest like the one in the picture would necessitate making the seats much narrower. Personally, I would not find the curved headrests comfortable, nor would I want the seats to be narrower than the ones Amtrak has now - others may feel just fine in a seat like the one in the picture.
Is it possible that some type of curtain that can be pulled down from the ceiling could create the wanted/desired separation without taking away seat width and some sort of fold-down armrest for those who want the division and left up for those who want to snuggle (or talk privately)?