I think there should be some pop-up option for categories in a report. Those options should be defining the state of the report, and the member reporting would have to select the option that describes what the report is all about before submitting.
There is already something relatively similar but not as part of the forum and instead as a browser extension, suchmoons's
One-click mod report, not for the faint of heart .
Additionally, every time you make a comment when reporting a post, it is saved so all you have to do to get an option is to enter first letter of your report in order to get all of them. So for example, if you reported post by writing "Low value post", next time all you have to do is enter "l" in the comment section and it will offer you that, and all other comments that start with "L". It makes a difference when you are mass reporting, trust me.