1. A client is a client, paid work or not. A failure to determine and meet the client's needs is the fault of whoever is providing the service, be it photography or something else. ...
If the photographer does not have a clear understanding of what the client wants, I agee that it is the photographer's responsibility to engage the client further. The proper interrogation of clients, I feel, is a valuable skill for anyone who takes pictures for "someone else".
Never ever accept a client saying "oh, just take some pictures, you know what we want." yikes!
Once you agree to take pictures for someone else, it stops being what the photographer thinks would be nice, and more what the client thinks will be nice. The skill of the photographer is in the taking of what the client wants and actually being able to produce it. Anyone can take a picture the way they want to. Taking a picture the way someone else wants, that's what makes this type of photography ... interesting.
Back to the OP's photograph. It is always risky to have the subject of the picture (in your case, volunteers) out of focus. It can work but for a lot of people it doesn't.
Good luck with it. You got a lotta advice in this thread... some of it may actually be good.