Using a browser-based technology requires a bit of a mental shift: you can save data permanently, and download files to disk, but it just works a little differently. You can't do the traditional read-and-write-files arbitrarily, because that's a huge security risk in a browser.
WebStorage provides permanent save storage, even when offline. You can download Array and Dictionary data as JSON for level editors, and AJAX them as project files to load them dynamically.
We might be adding more storage features in future, but I think everything's there - it's just a different workflow.