According to the pembroke standard the answer is yes. Do you HAVE to have a pembroke's tail docked? No.
The tail is docked at such a young age (2-3 days old) that it causes no harm to the puppy, and they have no memory of it. If it is done correctly and by a professional I see no problem in docking a dog's tail.
True that untrained people try to dock the tails on their own and often cause problems later on i.e. a malformed tail dock. These are the people who need a blunt object thrust upside their heads.Then there are the ones who think that it is a bright idea to dock the dog while they are an adolescent or adult. Again I wish bodily harm to these people.
It all comes down to choice. If you want a dog that you can register have the tail docked. If you just want a corgi for the love of having a corgi you can go either way.
I thought about my next corgi. I wanted to see if I could get a redheaded tri undocked, just to see what a pembroke corgi would be like with a tail. I could get a cardi but they are too big for me. I would like to stick with my pembrokes. Besides variety is the spice of life.
I guess it is sort of like circumcision. Is that inhumane? I don't know. I'm not a man. I'm not a PWC either, but Brodey seems happier than any other dog I have ever met that has a tail. I've never heard of a depressed Pem.
Actually, male circumcision in humans cuts a man's risk of developing HIV from heterosexual sex in half (http://www.nytimes.com/2006/12/14/health/14hiv.html?scp=6&sq=ci...). Similarly, circumcised men have a 25% reduction in risk of contracting genital herpes and a 35% reduction in risk of contracting HPV. (http://www.nytimes.com/2009/03/27/health/27std.html?scp=2&sq=ci...) And I'm still not certain that elective surgery on babies is ethical in countries that have other means of preventing such diseases. I think a better analogy than circumcision, though, would be if parents gave all children with imperfect noses rhinoplasty as a matter of course. Tail docking doesn't do anything for the animal or for it's utility to people. If 'the good of the breed' (in such a context, I have always found such a concept a little problematic) is your issue, there are some bloodlines with naturally bobbed tails. They have come into increasing use in countries that have banned tail docking. In sum, I love my baby's nubbin, but I don't think the lack of a tail is what makes Pembrokes what they are.
I grew up a farm girl and so have a different outlook on a lot of subjects than some people. And just like docking my fair lambs tail I have never had a problem with dogs tails being docked. I do however think people need to pay attention to what they are doing. My brother has a border collie that someone docked his tail too short and somehow this has led to him having serious health issues. He has had seizures through out his life and the vet said when he started these as a puppy that it was because of the way his tail was docked. I don't know the particulars but I do think people need to be considerate of what they are doing. My pem was born with a nub and I love her little wiggly butt.
Border Collies are not supposed to have their tails docked..it is not breed standard and they need their tails for navigation purposes for herding. The tail acts as a rudder when switching directions quickly. Their tail fur does tangle easily so that is probably why someone would dock the tail. I would not.
It makes me wonder if it was in some way to do with them herding, but then the cardigans aren't docked and they herd too. Actually I would think the docked dogs would have a more difficult time herding, since the tail would help with balance and turning quickly. I guess it must have been for looks.
Some sources (though not all) suggest that Pembrokes may be descendant from Swedish Vallhunds and that Cardis may be descendent from Tekkel dogs, the same ancesestors as dauchunds (ignore my spellings!) Some Val's are born with tails and some are born with stubs. Both types of tail are acceptable in the showing of Swedish Vallhunds. IF Pems really do come from Vals, I wonder if the earliest Pems were naturally stubbed puppies. We'll probably never know for sure, but I do wonder if that has anything to do with why Pems are docked.