From COM:Village Pump:
A recent change to the upload wizard seems to require users to enter an exact, day-precise date. This is of no use for artworks dated to, say "1883" or ""before 1932", or any value including "circa". My workaround is to enter a random date and manually fix after upload; my worry is that novice editors will take the former step but not the latter. Where was this change discussed? Andy Mabbett (talk) 12:21, 21 August 2015 (UTC)
There are many situations where a simple day like 2015-08-24 doesn't work as a creation date, mostly for older works where the specific date is not known. The older the work is, the less important the specific date becomes, with something like "14th century" being perfectly fine. Basically, Upload Wizard should provide a front-end for everything covered in Template:Other date, probably accessible through an "advanced" button.