
Simply speaking, I believe that this offers a more bipartisan format (assuming one group doesn't always receive the rebuttal slot). Why is it more bipartisan without a back-and-forth discussion? More often than not, panel discussions become an opportunity to yell talking points in response to a comment rather than develop ideas.
By focusing on panel discussions, CNN has historically gone for the entertainment value they provide. It also allows the network to push many big names onto the screen at once. One-on-one interviews allow the interviewees to say their side of an issue uninterrupted. This style has been a long-standing feature of many CBC broadcasts, especially shows like Politics with Don Newman.
CNN adopting this style means there could very well be less shouting matches and more discussion as a result. If the host of the show plays a fair and balanced role in the interview, the viewer will benefit by seeing constructive discussion and each side of the issue without yelling. Just in case you aren't familiar with the styles, I've included screenshots of each. What do you prefer?
Panel Style (Source):

One-on-One Style (Source):

Read more...