I would not dock it just to dock it, just like I don't do ears on my dogs, but honestly, at 3 days old, which is when they dock tails, the nerve endings haven't completely developed, nor the bone structure, and it's not nearly like amputating a full grown dog's tail. I personally would not do it if my dogs didn't come like that (except for medical reasons obvoiusly), but I dont find it nearly as cruel as doing the ears because at 3 days old they really don't have the same issues with it that an older dog does and it heals over within a day or two, providing it's done properly by a vet under sterile conditions and proper care is taken.