I'm surprised that anyone is surprised. It's Zynga. Their business model has always been slimey, and they add no value to society. Net negative, actually.
But who cares? After all, it's unlikely the next Vonnegut is going to spend his time playing MafiaWars instead of writing "Slaughterhouse Five" or anything.
I am reminded of the aphorism, "Time you've enjoyed wasting is not wasted time."
Fulfilling a compulsion is not actually enjoyable. So unlike most game-makers, I don't see them as creating fun.
What makes them worse than say, world of warcraft?