I understand everyone's concerns over the hybridization of fish and all. But, I see flowerhorns as an exception. These are fish that in the area that they were originally bred are prized animals. They were bred to have particular characteristics as not only a sign of success and status, but for religious purposes also. I wouldn't imagine anyone releasing them in that area, but this is all my understanding and what I have gathered from FH-specific forums which tend to mostly be Asian members who see the fish as such.
They are not fragile, sterile, or deformed. These fish are very tough guys, being able to survive not so ideal conditions. They reproduce like beasts if you get into breeding them. And also, their intelligence can be mind-blowing. Find someone who has had one of these guys for years and they are almost like a dog. I was won over on my last trip to New Orleans and a guy had his FH on display. He stuck his hand (well cleaned, of course) in the tank and the fish swam up and rubbed all over him. They register attention and interaction that you can't find in many other fish. I have spent hours training him and getting him to interact, which is starting to pay off. They are honestly the dogs of the fish world.
But, this is a fish I feel passionately about. I know people see them as unnecessary. I do agree that nature has produce amazing fish in all shapes and sizes. Nature has done a great job. But, if with a little tweaking, a new species is formed that is not a detriment, I see no issue. I don't agree FHs are on the same level as tattooed fish, there is no pain that is involved. The only pain that a FH will experience is when they are wrongfully purchased by someone as a juvie to be sold when they get big, pretty, and worth a lot of money and they go into depression and heavy aggression.