Thank you for the suggestion.
We have thought about it before and found its use not obvious because there is more than one situation: for example, if task 1 is due on February 10 and task 2 is due on February 11, you will move them to to February 12, while some users may want task 1 to move to February 11 and task 2 to February 12.
We will think what should be done, however, if solution is found, it will not be fulfilled soon. The nearest update is already being tested and will be released this month.