I've thought about this before and, like you, I've never had a dog that "required", for lack of a better term, a reason for cosmetic options. I worked for a vet a lifetime ago and witnessed it performed on many. They went through the surgeries, the splinting, the sutures, the Elizabethan (sp?) collars, the irritation, the infection, the crying, the multiple visits for re-splinting, and so on, for them to stack up appropriately - and all for virtually no real reason except show and breeding. But, I guess some do find that as a means of their livelihood. (my spelling really sucks these days).
On the other hand, I understand declawing cats. What is the worse of two evils? Saving the lives of cats? Or becoming so frustrated at the damage done by indoor cats that you turn them over or turn them loose?
The next thing that disturbs me is not removing dewclaws from dogs. The dewclaws serve no purpose and are routinely removed at such an early age (day 2-5 of age) that they aren't painful nor remembered. At best, they snag, bleed, cause tearing and infection and are much more painful to remove from adult dogs. To me, it is not an elective surgery and shows a sign of a bad breeder. It is inexpensive and indicates care.
Opinion.