isn't the tablet/ipad more of a media consumption device? It's better to watch a movie on the airplane with 16:9 panel, than the 4:3 panel. If people are okay with shrinking a movie into 4:3, why not shrink a financial report on a 16:9? Especially since you can and pane and zoom on a pdf file.
16:9 is only good for one thing, watching videos. People who read and surf the web outnumber those that watch videos alone.