I think it is worth doing.
If you read https://moodle.org/mod/forum/view.php?id=7966 you will see that Dan (Poltawski) is having a break from the integration team for the next few weeks. He is the person who oritinally implemented the report spam feature. I wonder how high up his priority list making enhancements is.
Certainly, automating spam deletion has been talked about. The tricky bit is to ensure that it cannot be abused to delete legitimate posts. (Hiding, and preventing mail-out, are more likely ideas, I suppose. Another idea might be to trust particularly-helpful-moodlers, or a more select group, to correctly identify spam.)
The think I would like to see, which might be easier, is Ajaxifying the UI. It is a bit annoying that it takes page-loads to report the spam.
I also wonder if we could auto-detect some of the common patterns of spam that we see.