In some odd user-cases it is handy not to show the selected range inside the calendar when it shows up.
Case: Lets say you have a range already selected. Then you click the current start-date in the calendar which pops up. Further you click a new date back in time. This sets a new start date instead of selecting the end-date. The combination of actions requires 3 clicks to set the new range.
If the user unfortunately clicks on the start-date, it's not obvious to some people that the next date you select is still a start-date, unless you are aware that the controller does not select ranges backward in the calendar.