I'm using a free add-on for that (see below), but it would not be a bad idea to have in the base. The add-on uses a group permission, too, so it is not limited to admins, but to any group the admins choose to grant it to. In my case, I created a group with just this permission so I can just add it to any user with a use case.
Adds the in-line moderator option "Change Post Date". New Permissions Change Post Date Contributing features or bug fixes Please create a Github Pull request via the "More Information" link. Contibutions If you appreciate this addon, please...
All that said, this is probably a duplicate suggestion. The fact that there's a couple add-ons for it indicates some interest.