cropped ears is an un-necessary comsmetic procedure unless you're actually showing or working the dog... actually, in some countries it's even illegal to have a dogs ears cropped or tail docked. My Glen terrier was bred overseas, the breed standard in the US is to have the tail docked, he still has his tail and I think he looks cuter with it.
While I see that in some cases it is necessary (heavy tailed working breeds in particular), most cases it's just a matter of what WE want the dog to look like... and in pit bulls its to make them look more badass (or in the case of dogs that are used for fighting, to prevent excess injury from having ears/tails ripped off)