I used to live by the firm conviction that in any good photograph, something should be sharp. In recent years, however, I've come to believe that this "rule" is actually rather arbitrary. Why does anything in your image have to be sharp in order for the photograph to be good? I've come across many photographs that are only softly focused, if at all, that I must confess are extremely good photographs.
Of course, I'm not issuing an invitation to be careless in your photography, and if a photograph comes out blurry, just call it "artistic." But if photography is more than just documenting the presence of an object in space and time, then we need to leave room for all sorts of creativity, including de-focused or softly focused images. These types of images often tend toward the abstract, but the emphasize the aspects of composition that shape our photographs--design, color, etc.
The challenge in this type of photography is letting the viewer know that your focusing decisions were intentional--that they are part of the composition of the image. You don't want to give the impression that you made a mistake and decided to try to pass off your mistake as art. You want to present an image where the soft focus contributes to the composition rather than takes a way from it. But practice will help. Now on occasion I'll take a sharp image and a soft image to see which I prefer. On occasion I prefer the soft image.