It was suggested a while ago and the community has just supported it (voting
39:0 now) to block uploading media files by not logged in / fresh users -
similarily to the enWIki.
Users' accounts should be at least ca. one week old to upload files.
The request is due to a large amount of copyright violating/redundant images
uploaded by new users. Checking and deleting it requires a lot of effort from
sysops. What is important, vast majority of such errors is made by newbies so we
want them to learn more about the project before upload anything.
Thanks a lot for your help here.