From a basic workflow perspective, it can be frustrating to have to drag a task onto the calendar and then manually set a due date. In 99% of cases, all I really want to do is move a task that's in my inbox or a list down the road a little - i.e. snooze it or schedule it to be looked at later on that week.
What i'd love to be able to do is right mouse click on a task to bring up a sub menu and select 'schedule' and then in one click be able to either select 'Later today', Tomorrow', 'Next Week' or a specific date etc.