Most people here seem to hate online games, and taming / controlling pets was a major feature of Ultima Online. So their reaction to this is predictable.What's wrong with pets? I think they are pretty cool.
Me, I'm all for it! It was a blast taming creatures in UO and walking around with an army of critters at my command. The higher skilled tamers even managed to tame dragons.
And really there's no reason something like this shouldn't exist in a virtual fantasy world, even a single-player one.