The only ethics I consider when making hybrids is what to do with the fry.
If you sell them on, you risk polluting the already watered down gene-pool and this makes some "purists" very mad I can assure you.
If you keep them, you'll need some more tanks as the fry will obviously interbreed as they get older.
It can either get very expensive, or border on the line of damaging the aquaria trade.
Your choice.
I breed hybrids simply because I get fed up with all the fancy varieties on the market which have been weakened by inbreeding, I keep all my hybrids and any I can't look after go to people in my club, or the surrounding area with the expressed condition that they must not release them into the aquatics trade.