Clients can also opt to allow you to see unapproved post. So it kinda already is.

I agree though it's basically the same thing and the definition of the community should be such that you pick either approve by default and then you delete post you don't like or unapproved by default and then you approve post.

I can see with spam being such a big problem why approve by default is not a priority.

You can actually submit that as a PR to the spec though if you add that functionality to a client. It wouldn't be that hard.