Cropping is a tool. Just as choice of developer or film and tone of printing paper. To choose not to crop if you have the ability to is to introduce an artificial handicap IMHO. Now if you want to always print full frame and that's part of your artistic interpretation, then all the power to you. It's just that some images are improved with cropping. I've done some where a wide narrow presentation looked best and I didn't have a panorama camera laying about.
One of the nice things about using the 6x6 sq format is that I can get both vertical and horizontal croppings. Although I generally end up composing for the format used I certainly don't rule out cropping on some ethical grounds.
I may be wrong on this but I think even the contact printers can still crop if they so choose.