It can be a realistic fantasy. And they're always better with the option of death, anyhow.
See, now there's not much you can really do with the pets. Oh, sure, you can buy stuff for them, but that's kinda boring. And the games get old after a while.
So in my opinion, there is one point for them - the games.
And a lot of points against them. Though I must admit, they were fun for the first... week or so...