So on the one hand, I like the idea of preseeding the defaults in studio or other authoring UI, so that instructors know what options are available to them. On the other hand, I dislike setting these defaults as defaults for an unconfigured XBlock, because it means that you end up with something that looks plausible at first glance, even when you haven't set it up properly. While convenient for development, I worry that this will be confusing in the long run.