I have no problem with a PR to update the NIP. But if we change the contents of kind-10002 to say 'inbox' and 'outbox', how many existing implementations will that break? Normally we don't break anything. We could suggest backwards compatibility in that 'read' means 'inbox' and 'write' means 'outbox', but in that case clients that don't do that will not understand these new fields will fail to get the data they used to get. I think it is more important to not break existing stuff. NIP-65 already explains what 'read' and 'write' mean, and I updated those explanations to be even more clear, so at this point the way forward is to just spread the message.