I guess it's a matter of principle. Where is the line between stealing a hamster and frying it, and stealing a horse and stabbing and whipping it for a week until it dies of blood loss or exhaustion? It shows you are a sadist, and no animal should get tortured without reason.
Yes, a criminal record is too much, as it's nothing criminal in itself. But he most definitely deserved a pnishment, not only for stealing and killing a hamster, but also the way he did it. I think it does matter that the hamster has - most likely - been fried to death. Especially since I believe that even if that asshole wouldn't have been stopped, he still wouldn't have eaten the hamster, no matter how drunk he was. To me it just looks like he was drunk, he lost all the scruples which society taught him, and just wanted to see a small animal die a cruel way. I think society should show him that being drunk does not save him from the bad consequences of unwanted behaviour.
The best punishment though I that his name and picture are known now, and whoever gets in touch with him has chances to recognize him, and he will suffer from the disgust he has caused. Especially since all his relatives, friends, tachers and so on will have heard of what he did.