Without a conflict, there is no need for a resolution. Conflict is the basis for any story. It propels the story forward. There is an inner or external conflict or both in the life of every person. Because some writers choose to share that conflict, others can relate. Conflict causes a story to be interesting. Why does conflict and struggle immediately grab the reader's attention? The reader usually can relate in some way.
At the very introduction of the conflict or struggle, the reader is interested in a solution to the problem at hand. Often the reader has a solution that perhaps even the author has not imagined. Life is all about a conflict, a struggle, inner strength that comes from the struggle, and then the wisdom that comes from the resolution.
We, the readers, thrive on conflict and yearn for resolutions. We anticipate the happy ending. We endure the pain of the conflict and struggle in order to be relieved by the happy ending. Readers hate stories that end without a resolution. Immediately, the reader is imagining the "what if" for an ending. We, as readers, as emotional human beings, long for the murderer to be revealed and receive his or her just punishment.
No conflict, no story. No resolution, unhappy reader.