"Can not delete ConfigSet as it is being used by another collection"
I would add the collection name to the message to make it more helpful?
I've allowed deletion of configset when force=true, but I really believe we shouldn't allow that.
I tend to agree with you on that. The problem is, from what I've seen, that the collection becomes unusable after you delete its configuration, even if it's later restored. Perhaps it was a point-in-time behavior of the code and has been fixed since then, but I prefer that we don't allow forcing the deletion of a configuration.
Why would a user want to force-delete a configuration, when there are collections that use it? What good comes out of it? Perhaps we should add this 'force' support after we see an actual use case?