I would find this useful for one reason: my custom moderator flags often contain extensive Markdown to link posts, often that has to be hand-tweaked to be short enough to fit in the character limit (for example, these posts ([1](/a/12345), [2](/a/23456), [3](/a/34565)) are all spam for $site (See [here](//link.to/context) for more posts from this campaign)).
If I had some way of getting the Markdown, this wouldn't be an issue, but a simple copy/paste of the flag text doesn't get me what I need to recreate the flag.
This often comes up for flagging bad reviewers: I frequently stumble across additional bad reviews by the same people, but I don't always save the original flag text to add the additional reviews.