I have no basic problem with hybrids, so long as they are labeled and sold as such. But there are lots of not-quite-right ideas floating around in this thread. Species crosses in the wild are not common, but do occur where "normal" species barriers to cross breding break down, whether that happens naturally or by man's invervention. Both cases happen.
Man also selects for desired traits, sometimes by simple selection, most commonly by back- and cross-breeding of different "strains" or of mutations. We would not have long-finned varieties of fish if this were not done, nor albinos, nor the many varieties of Angelfish or Discus, or even the handful of forms of Tiger Barbs. Since fixing of mutations occurs in the wild as a basic part of evolution, I see no basic issue with using that to our own needs or desires. It has been done historically with dogs, cattle, horses, sheep, goats - all of the domesticated animals - and is on-going. As ornamental fish become domesticated, it is bound to occur and already has history for goldfish and koi, only modern history for tropicals.
I object strongly to sale of hydrids without the information being supplied that they are hybrids - mixed cichlids are very common, and few folks understand what they are dealing with when they buy them. These are "pound puppies" at the worst - individually they may look and act great, but breeding is iffy if someone thinks they have a species.
Genetically altered fish were done as indicator fish, whether as markers linked to another hard to detect gene or as biological pollution indicators. It in no way different than the modifications which have historically for domesticated species other than the sophistication of the techniques used. Humans have and will continue to modify their domestic stocks. Whether you approve or disapprove of a particular product of the manipulation is unimportant other than to you personally - the modifications themselves have historic and wide acceptance and will not stop on either animals or plants even single-celled organisms (bacteria, yeast,etc.).
I pesonally do not like long-finned versions of fast schoolers, such as Danios and Barbs. Fine, I don't buy them. I don't like distorted Cichlids. Fine, I don'y buy those either. Those that do like them are free to vote with their dollars and their care. End of discussion.