One reason Kristin might be more vocal about this because of her personal relationship with Ariana, which started with Ariana coming to the stage door to meet Kristin, after he first attendance at the Broadway show when she was a kid. It was during that meeting, I believe, that Ariana expressed the goal of playing the role herself one day. So Kristin's excitement about this trailer specifically makes sense, because it's really the first peek into Ariana's actual performance (the first time we hear Ariana's voice as Glinda, other than just saying "You're green!" in the teaser that was shown during the Super Bowl. As happy as Idina is for the film, and for Cynthia, the personal relationship isn't DEFINED by Wicked like it is for Kristen and Ariana.
For the award ceremony I want idina to be elphaba again defy gravity or singing for good in costume while Cynthia doing the defying gravity on the stage