I have never had a dog's tail docked. I have several dogs with docked tails, because I rescue a breed (smooth fox terriers) that have docked tails by breed standard.
Most likely, I will never buy a purebred dog as a puppy that gets a docked tail, so the point is rather moot. I will probably end up always getting my dogs through rescue or adoption as adults.
But, if I were to buy a puppy of a breed that normally gets its tail docked, then yes, it would be done. Tail docking is not cruel. It is done when the puppies are a day or so old. It is very quick, like two seconds, literally. I've seen it done. It heals quickly, and the puppies are too young to lick it and cause problems. I am quite sure the 24 hour old puppy has absolutely no recollection or lasting trauma from the two second procedure. It is, honestly, just like having your human baby boy circumsized.
I like the look of docked tails on certain breeds. IMHO, a cocker spaniel or a Jack Russell or a fox terrier simply does not look the same with a long tail.
I am, however, not in favor of ear cropping, for me personally. That is an entirely different thing, IMO. Ear cropping is an involved, painful procedure done when the dog is much older. It takes a long time to heal, and the dog must be kept from scratching or rubbing its ears. In many case, this requires wearing an elizabethian collar for some time.
To each their own. Honestly, if someone loves their pet and provides it a good home ... who cares if they like docked tails or not? That is the LEAST of many dogs' worries. If you don't like it, don't do it. But if you do like it, go ahead. It's not cruel, it doesn't make you a 'bad pet owner' by any means. IMO, docking is a very, very small issue in the global issue of animal/pet problems.