Anyone who's ever been on an airplane for like, a second, knows that it's not comfortable. If you have to fly for more than two hours, you're going to come off the plane a smidge rumpled. A mini and platforms is not going to get you around that, and on top of it you'll also be cold and uncomfortable.
Jessica and Kim are doing way.way.way better on the airport style front than Beyonce and Victoria. (Also, if I had my hair pulled back as tightly as VB does, my head would explode.) Layering is key: too hot? Take off the blazer. Too cold? Wrap the scarf!!