On Windows, selecting the tracks and holding Alt+SHIFT while you mouse-click on one of the track's outputs and change, will do to all selected.
A faster way is to select the tracks and move to a Routing Folder(and check the box to change routing). That will create the folder track(which works just like routing thru an AUX track) and set the routing in a single command(if you are on a recent version of PT).
But, I do agree that dragging across could be very handy, for outputs, solo's, mutes and probably a few other things