@dustbunny isn't random at all ;)

The free enrollment was designed for and favors accounts that cannot afford supporting the bunny from their own wallet. Naturally, such a service has its limits. Users with sufficient stake will not get the bunny's attention all too often at all unless they support the cause with a delegation. Making a delegation will also increase the priority their dust has in the bunny's queue.

Either way, @dustbunny always is and remains "basically free", but if you need more fluff, you've gotta help the bunny do it's thing, too ;)