First a bit of
When I became a moderator, there were two responses to flags: valid or invalid. There was no formal definition of these two terms; I took “valid” to mean “you were right to bring this to our attention” (regardless of whether I ended up choosing the resolution requested in the flag) and “invalid” to mean “so what? I can't do anything about this situation”.
A few weeks ago, the wording was changed to “helpful” and “declined”. There was no prior explanation of the change (hence Robert's question). On the face of Jeff's response, it seems that my interpretation was right — but based on the names alone, I would have thought that I should be using “declined” more often (whenever I'd decline to do anything).
A few days ago, moderators were publicly berated for declining too many flags. Or maybe this was just meant as a clarification — I'm honestly not sure if this was meant as a reproach to the community moderators, but it sure felt like one. And it didn't clarify anything for me: was my interpretation of valid/invalid right? Or should I just forget the “decline” button exists?
As of this morning, moderators must enter a reason for declining flags, but cannot enter a reason for marking as helpful. Now I'm really confused.
Is the mandatory feedback supposed to introduce friction so that moderators don't decline flags? In that case, I have a simpler solution: remove the “declined” button.
Are the two resolutions now “don't provide feedback” and “provide feedback”? In which case, please change the wording on the buttons. There are plenty of helpful flags for which I'd like to provide feedback (“We don't do community wiki for that kind of stuff any more, please read The Future of Community Wiki, I'll close the question because it doesn't look salvageable.” Or “Yes, this question is off-topic here, but the mods on X don't want it either so I won't migrate.”). Conversely, there are plenty of unhelpful flags which don't require any feedback other than “WTF”.
Should we keep using “declined” as before and write a user script that automatically feeds “WTF” as the reason?
So, my support request is: please tell us how we're supposed to respond to flags. Preferably before making UI changes. And make the UI internally consistent.