I find myself entirely on Pincus' side. The author of the article mistakenly assumes that Zynga's value is in Farmville/Fishville/Poker. It's not. Pincus once said that if he could re-do tribe, he would instead build "a platform for testing ideas about how to make social networks," or something. With Zynga, Pincus has buildt an entire company mechanism for figuring out how to make money from FB games, I assume revolv…
So really it's not so much about getting people to pay - it's about getting people to play. FarmVille is famous because 84 million people play it.
World of Warcraft still makes more money than FarmVille, but World of Warcraft has nowhere near that userbase.