The problem is that Zynga isn't operating in a vacuum. Sales lost to Zynga do hurt someone else.

In the University paper example, how would you feel if the number of A grades available were limited, and because someone copied a previous year's A-paper, someone who deserved an A now received a B? What if that person was you?

There's a spectrum between inspiration and impersonation, and Zynga is clearly on the impersonation side. IMO, it's extremely disingenuous of Pincus to try to pass of his game as somehow derivative of Sim Tower or Yoot Tower. I'm surprised he wrote a memo at all, considering that Zynga employees aren't stupid - they know what brings in the money, and it isn't coming up with fun, novel, interesting games that are built upon the shoulders of giants.