There is a scene from a movie where a character says "Gripes go up". Which is logical in organizational charts. I can't spend all day complaining to my subordinates. But I can write my gripes in 15five and think "wow, I just got a lot off my chest about situations at work that halt productivity in my days" and it goes to my supervisors or upper-management. To the people that should hear my gripes. The concept is also effective since putting concerns in writing is effective, but 15five is not simply an email to a person. I would think writing the same questions/answers asked in 15five in an email could go unnoticed or thought of as a negative.
I couldn't really write about anything I dislike, honestly. If there is anything missing, I'm not aware that I'm missing it.
15five is really a neutral space for letting work complaints just "come out". It's a great tool too, where without 15five, I would probably have limited to no communication with personnel in our organization. A tool like this really addresses how many of us feel in organizations, where a culture may exist, where you'd like to speak up about topics, but either can't effectively get your input to management during meetings or don't have the resources and time to push out ideas and concerns. For me, 15five helps alleviate stress at work by allowing me to take time to voice my thoughts to a group that will read, respond, and at least acknowledge my feedback. Daily communication is often all on-line too, so it makes sense that we can write out work concerns on-line as well.