I agree its an important part of privacy and control over your own content, however in regard to censorship resistance this ability to withdraw your content can prevent a chilling effect. On the other hand, any promise to delete content can never be a guarantee since once its been transmitted to a relay it will have been rebroadcast to untold places and any perceived promise to delete may give a false and dangerous confidence to the dissident
Discussion
I agree, this is why it should be the standard.
I wonder how this could be achieved.
If not, oh well!
Once a secret is revealed, whether intentionally or not, it can never be concealed again without the use of force.