I actually think it's a good thing that there isn't a "one-click report" feature built in to the forum. It is extremely easy to mess up and fire off a bunch of inappropriate reports, so forcing people who want to use it to both have to spend some time setting it up, as well as have a basic knowledge of coding, prevents spammers and scammers flooding the report queue with nonsense.
IMO that is spot on. Anything too easy could be abused. Soon after we might see temp bans for "report spam"
Would a system which providers reporters with "Suggested comments" or a checkbox for the most common reasons not be fairly useful then, as it would serve to standardize a lot of reports...
Not too sure about the checkbox and standardization. Also need to think about different languages as well. Since being a patroller I learned how to write "spam" in 4-5 languages so far

))
This is an idea I liked:
Maybe the button can be 'semi-disabled', ie it gives you a prompt like you have already reported this, are you sure you want to report it again?.