I use my camera lens to frame the world around me into finished prints so that other can see what I see, how those images are framed or cropped can be a matter of debate among photographers. I feel that cropping is a personal preference, with each photographer having their own unique style in terms of how they look at the world through with their cameras and present their finished work, some may feel that cropping an image makes for a stronger image. Many photographers believe in presenting a full frame image with no cropping, because of my photojournalism background I have always admired the work of , Henri Cartier Bresson , the originator of on the street photojournalism who never liked to crop his images. I also love the work of Edward Weston's images from 8 x 10 contact sheets, where he had no choice but to crop within the camera, I don't think Ansel Adams cropped many of his images either.
As a working photographer making my living as a staff photographer for a daily newspaper my images get cropped all the time, sometimes by the editors or by myself when I am editing through my digital images, if for instance I am editing through pictures from a sporting event like hockey , I will often crop an image for more impact so there is less "dead" space around the players, with other non sport pictures I will leave them full frame if the picture conveys all the elements of the story.
In regards to my personal fine art black and white work featured on this blog and my website that produce on my time off, I can pretty well say that all of the images are "full frame" meaning that I compose them in the camera out in field for the shape of the camera format, usually using my 4 x 5 , 5 x 7 or 8 x 10 cameras. I also use a Fuji 6 x 9 medium format camera from time to time and I like to print these images in with a bit of the outside film boarders showing.
I think one of the keys to making a fine picture is to have some kind of idea when one is shooting an image out in the field as to how the finished image might look, whether you intend to crop it or leave it full frame that way when working on the image on one's computer ( or in a darkroom ) the photographer will have some kind of sense of where they are going with their image(s) instead of just guessing and hoping for the best.