The thing I have against hybrids is stuff like: If you want to get a trimac, you'll almost always end up with low grade fh's. Basically they are bad for the gene pool if you want a pure fish. Some people don't label hybrids as hybrids, such as the rd/midas. Peeps try to pass off low grade fh as trimacs, etc etc. If any of my fish hybridize, I feed the fry to my other fish.
I can understand people liking flowerhorns though, I just don't like the fact that hybrids often end up making the fish that are available in the hobby, unpure.