Man has been breeding fish to suit his aesthetic tastes (vs. what's natural) since like 200 AD with colored carp. The foundation of the aquarium hobby was and always will be fancy fish. The first black angelfish was a big deal. As were high fin "platies" and red oscars and all of the rest.
They're what many people want. Think of it this way: How many people would choose a small, short-finned, brownish wild-type betta over a long-finned, double-tailed metallic purple one? In terms of its viability in the wild, such a "fancy" betta is a monstrosity. But that doesn't keep legions of both commercial breeders and hobbysists from developing new and more beautiful (or hideous!) strains of fancy bettas (discus, livebearers, angelfish, flowerhorns, etc, etc, etc.).
My point is this: One person's monstrosity is another person's picture of beauty. Aquarium keeping is inherently unnatural (as is breeding fish in a glass box). It really comes down to personal taste.
As with anything else, some people are in it for the money and others are in it to develop interesting and beautiful new varieties of fish (and to compete in fish shows).
What's clear is that developing quality lines of fancy fish takes a lot of skill and time (and culling lots of fish). There are far easier ways to make money!
The idea that you shouldn't be able to buy, sell or breed blood parrots is a non-starter: impossible to define, regulate or enforce. There are a million more important things in the world...
Matt