Interesting. If you chose a pin for your card that was the result of modulo arithmetic with some part of the card number (last four digits, for example, but perhaps something more obscure), you would have to write on the card at all.
You probably wouldn't want to do that: If the pin was somehow compromised, then the attacker would likely try the same compromised pin number in other places. Using different pins for each service avoids this attack.
