I also disagree with cross-breeding however it is a hotly debated topic. Of course in the day and age of ultra-specifying animals into branches and branches of sub-species there will be some cross breeding in the wild. That's in the wild though, and even though occasionally higher forms of inter-species breeding occurs, it is my opinion that as a hobby we will reserve much more respect if we keep our breeding endeavors clean.
As per the dog comment, it pertains to a much more high profile drama, and that is looking for the latest colour morphology. I'd like to say that I disagree with this, but even I"m tempted to breed my high salmon coloured boa constrictor to another similar boa in an attempt to create something new and exciting. The profit would be nice too. The problem with this, as obviously seen in dogs, has already begun to show up as blizzard lizards are weak, hypo sliders have poor shells, and albino iguanas are sometimes blind.
As much as I enjoy playing the devil's advocate in these discussions, I think it is hard to imagine the reptile hobby in 100yrs as the dog hobby is today, and thus the issue is ignored.
Will I buy a pie-bald ball python? I'd love to if I had the dough, but do I agree with the breeding done with this and other traits? No.
Yup, I'm a hippocritt on this subject, but I don't think I"m the only one.