In a perfect world every photo I take would be perfectly framed and composed. All the elements of the photo that I want to be there would be, and anything that I didn't want in the image wouldn't be. Unfortunately that rarely happens. I would love to be able to tell you that every image I shoot is exactly the way I planned it. But .....
I crop. Some photographers say they never do, and if that is true then some wonderful images must wind up on the cutting room floor because of unwanted elements in the frame. I crop because of the way I shoot - holding the camera at chest level and shooting without lifting it to my eye. My images very often have a slight tilt to them, and if it works for the shot, I include that. But it often doesn't work, so I straighten the shot. Sometimes the main subject is not placed exactly in the frame where I want it to be, so I crop and adjust it to get the composition just right. I usually shoot with a very wide angle lens so I get enough space around the image to have room to do this. I don't think cropping is any different than dodging and burning, or adjusting contrast. It's another tool in the kit.
In this image I wanted to create a feeling of depth and motion to move the eye through the shot. That's created by the diagonal line that runs from the lower right corner to the other side of the image. The vertical lines of the main subject interrupt the flow of that line, and say 'Here I am. Look at me'. In the original image they were off center. I always try to maintain the proportions of the 35mm negative in the crop. Some people like square images, I like the opportunity to use the frame to create the feeling of dimension. The three characters in the center of the image are in focus, and the outer edges are not with an increase in blur as the background recedes. It gives the image depth. That's the way I saw this image when I shot it. It's not what I got in the camera - so I cropped it. The moment was gone in a second. No chance to check the LCD to see if I got it right and reshoot it if I didn't.
And by the way, when I was shooting film, a long time ago in a galaxy far away, there was absolutely no way to tell if I got the shot until I got home, loaded the film onto the spool, developed it, and made a contact sheet. Should I have not made a print because I didn't get it right within the frame?