We have 2 clients requesting this for different reasons. But one clear reason is for sorting by custom dates alphabetically when put in the task name. Zeros help solve the alphabetical sorting issue of numbers, since 0 comes before 1 alphabetically.
The other reason is for passing the data to the government and a little more specific, but they asked for leading zeros as well since they have to remember to use a WF function to add it back in every time.