I agree with you, nightowl that there is nothing wrong with emotion, and without genuine affection from its owner/keeper/carer no animal is going to get the care it deserves. However the emotion must not cloud recognition of what is best for the animal, or for the whole species that animal belongs to
It can be better for the animal to be humanely killed than to be allowed inhumanely to live and suffer because no-one will take an unpopular decision.
At times it can even be better for the species that an individual animal does not breed or sometimes does not continue to live. That is an even more unpopular and difficult decision, but those responsible for animal welfare have to be prepared to face the possibility.
Cute babies and attractive furry things evoke oohs and aahs, naturally. But reptiles and creepy crawlies do not. Would there have been such an outcry if there had been a population explosion of naked mole rats who could not be found suitable homes and had to be euthanased? Are we more concerned about the dwindling numbers of giant pandas than we are about the similar danger to poison frogs (who are actually very pretty things) ? Are there hundreds of comments on Facebook about the male day-old chicks who can find no home and are used as animal food (they are cute, too, and appear on all the Easter cards)? Do we stop drinking milk because of the calves who must be born to keep the cows lactating?
Concern for animal welfare is very patchy, and not at all logical.