Part of the reason to make timely updates to Cortana is to keep her off-the-cuff comments timely, and filled with relevant references. The software giant also plans on loading Cortana up with AI so she will learn each user's different needs. One study used by Microsoft showed that 40% of the time spent with a device carrying Artificial Intelligent, is wasted on "chit-chat." That explains the focus on making her banter current, timely and relevant. Since Cortana's pages are rendered in HTML5, the guys in Redmond can make these updates without having to send out an OS update to Windows Phone handsets.
Microsoft wants Cortana to sound less robotic, so the voice used will be the one belonging to Jen Taylor, the voice of Cortana in the Halo series. But Microsoft also has to deal with some regional requests. In China, for example, the virtual personal assistant has to have a voice that sounds like it is smiling. And to make the program more human-like, Microsoft interviewed real-life assistants to understand how they interacted with their bosses, and what things they did that made them successful at their job.