3CsMommy
My babies Rock!
I just don't think it's an accurate comparison between chinchillas and animals that have been domesticated for over ten times as long.
The history, confirmation, and practices behind breeding dogs v breeding chinchillas obviously differ greatly, but the value I see in examples like that is this: all of the animals in question are being genetically manipulated by humans. And as humans, we like Big, we like Pretty, we like Shiny, and the more of them we can get, the better.
While the animals being discussed are apples and oranges, the trends humans doing the breeding consistently select (Bigger body size being the main one discussed here) are very alike, regardless of the species.
I think cautioning people away from only breeding for size or only breeding for color is necessary. Look at how many people thinking of breeding or planning on starting we have crop up here every day wondering about genetics, wondering if a 600 g female is "big enough" without really knowing if she's got a clean belly and sturdy coat. All the traits should matter equally for a healthy captive chin.