When creating a new file, the file gets named based on the current date. For file based CMSes, this is usually not the desired naming schema as the file name often becomes the URL slug. I'd ideally like to see a configuration option to choose what field the file name should be based on and a "slugify" option for it (if text). If this means holding off on writing the file to disk until this is available, I think that's an OK tradeoff. If it's not for you, then automatically renaming the file after the selected field is changed, or providing UI attached to that field to update it, would also work.