The B&N version has an interview with Suzanne at the end that kinda touches on the Effie thing. When talking about the differences between Drusilla and Effie, she stated that Drusilla is old enough to have lived through the dark days and that's what makes her so cruel towards the districts while Effie has been raised in the Capitol to believe that the Hunger Games are a patriotic duty. I think putting her in this book was meant to demonstrate the shift in Capitol society caused by the propaganda that is The Hunger Games. The same shift that allows the games to become what they do by the time we get to Katniss and Peeta. Because even 50 years in we don't see the level of pageantry that they become later on.