The reason deletedtext is a sysop-only user right is that some deleted articles may be copyvios, attack pages, and similar stuff that needs to be kept out of the public eye. However, the metadata such as edit summaries, revision lengths, revision timestamps, etc. are usually not such a big deal.
If it is desired to delete individual edit summaries, that can be done using RevisionDelete (if necessary, a tool analogous to Nuke can be used to do it en masse). If page titles are objectionable, the page can be moved to an innocuous title (e.g. maybe a title based on the page ID, such as "page1234" before being deleted, and then the page title part of the log page move and page deletion log entries can also be deleted.
We already keep publicly available all log entries, even those pertaining to deleted pages, so this is just taking transparency a step further by also putting out there revision metadata that can be helpful to researchers (without the need to go through the red tape needed to get added to the researcher user group) and to deletion reviewers.