Whatever the case, hybrid or mutation, the problem I have with them is they displace knowledge of and interest in naturally interesting and/or beautiful species with a malformed novelty, and their popularity multiplies this effect. I'd prefer to see fishkeeping as a gateway to education about and appreciation for nature, which provides its own interesting oddities. Dyed, tattoed, glow in the dark, and certain other novelty fish are distractions and obstacles to what I'd like to see in the hobby.
Sure, hybrids occur in nature and nature does its own linebreeding, so I'm not against all selective fish breeding. It's a matter of degree. Even in natural fish I have my preferences, beauty's in the eye of the beholder, but some fish simply take human manipulation too far for my tastes.