We should at least factor in how natural or pleasant their existence is. Or else a maliciously engineerd creature which spreads like crazy but is genetically bound to suffer immensely all their life is somehow preferrable over a local population of happy birds.

The species we use to harvest their products and body parts are often unable to survive naturally, some suffering from accumulated genetic defects, like being unable to support their artificially increased body weight.

If we don't need to reserve pastures for human-cows, there might be a chance for natural species to grow their numbers again.