Yogosans14, I think it is incredibly smart and open-minded to bring up this topic as people do feel strongly about it. Kudos to you.
I Completely agree with LayzorBeams. I understand the breeding for specific characteristics--dogs, cats, garden plants, horses, and aquarium fish are just a few common examples. However, when the life in question has been so overbred that normal things are hampered (the inability to bear puppies naturally in Old English Bulldogs forcing all births to be caesarian section, for example--or hairless cats who can't stay warm and must have heat pads scattered all over houses--or dyed aquarium fish whose lives will be cut short because of it). Breeding goldfish for color or longer fins, or even some body variation seems reasonable. But those with upward-facing eyes, balloon sacks around their eyes, impossibly barrel-shaped bodies, etc. can't compete with normal fish in a tank. Additionally, many fancy goldfish are prone to air bladder issues. Just googling "swim bladder problems in fancy goldfish" is enough to give one pause.
If you can keep those you have healthy and well-fed, good for you. At some point, humans do need to consider what we are doing to creatures under our care.
Full disclosure: I keep two comet goldfish in a 55 gallon lightly planted tank along with a small school of white cloud mountain minnows. Watching the comets swim is lovely--they are sleek and elegant.