You're totally right. We originally built a backend service with a catalog to curate widget.json as part of a paid service. We couldn't work out the economics (and it felt a little weird charging when we didn't make the content itself), so we released it as a more open, DIY-friendly thing. On https://wd.gt, we've got a few examples of static widgets, but they wouldn't be very useful to subscribe to. I'd like to build a few that are worthwhile (e.g. NASA image of the day).

Great idea on the editor too. We were pursuing a web-based widget.json editor that had a live preview and didn't require you to necessarily type in json, instead it would have a little wizard or even drag and drop elements to lay them out.