Unfortunately, that would make it hard to provide various features server-side, such as code highlighting, and would require JS on the client (and also break raw file downloads, etc). It would also make the editor plugins much more complicated (right now they just POST to an endpoint).

We think that not listing pastes, having them expire soon by default, etc is a good compromise, as we don't claim perfect privacy, just that pastes are always sort of "unlisted".