I have the opposite of that problem. There are a lot of animals I have experience with and would love to own again but can't because I'm not able to suit their needs. Birds being one.
My brother has fish tanks. He thought they'd be 'easy'. What a joke on him. One is over-run with snails now and he's had to get Assassin snails to get rid of the others. He also tends to have too many fish. He over feeds them as well, then bitches that the water stinks and he has to change it all the time. He's a doof.
Versa I don't think it's heartless I just think it's carelessness or ignorance :P most people are taught fish are easy so they just take care of them like it's nothing -_-