Simply because they make awesome babies no matter what you breed them with. You'll also get a ton of variety out of their offspring. If you breed a blood parrot with a flowerhorn you'll get kamfa flowerhorn. Breed it with a synspilum and you have rainbow king. Breed it with a texas for a few generations and you have red texas. Breed it with a midas or red devil and you'll have some sweet faders. Not to mention all the other fish you could breed it with that haven't been tried. I'd like to see them crossed with parachromis, different vieja/paratheraps, and a festae would be sweet too.