I think it's pointless to debate whether cloning a mammoth is 'good' or 'bad', and the results of the poll bear this out; most people voted other. It's not bad, it's good, it just 'is'.
Personally I don't have a problem with it. At the end of the day it's just one animal. Ethically maybe it's a little cruel to bring this solitary specimen to life for the sake of studying it and displaying it, but I suspect such a creature would be one of the best cared for in the world. It would be worth too much money to treat poorly.
I find the idea of bringing back a mammoth scientifically interesting, possibly useful as a testbed for more advanced cloning/reproductive techniques that might be adapted to other uses. Anyone who think that the species itself could be brought back is stretching their imagination.
First of all it would be extremely difficult to bring back a functioning population that could reproduce on its own. Chances are it would take several attempts (I read somewhere about attempts cloning cattle being successful only 30% of the time) to get a living specimen as a result. Finding enough viable DNA to create one mammoth is hard enough. Finding enough to create a group that wouldn't soon inbreed and die out would be an order of magnitude even more difficult.
Secondly, even if you did create a viable herd of mammoths, they won't behave like mammoths from the Pleistocene did. They can't. The idea they could only holds true if you believe they'd have some sort of instinct that would guide their behaviour innately and the likelihood of that being true is remote at best. A mammoth was probably not significantly 'dumber' than a modern-day elephant, and elephants learn all sorts of social behaviours from adults in their herds. Would a cloned mammoth that bred with another cloned mammoth learn how to care for that infant mammoth? How would it? It would have never seen another mammoth care for an infant. At best it might learn behaviour from an elephant surrogate but an elephant surrogate will teach it how to be an elephant, not a mammoth.
You can't really bring back an extinct species. You might be able to make copies of extinct animals (and contrary to some assertions above they would be copies, not some hairy franken-elephant, despite using a little elephant DNA to fill in sequence gaps), but the species will never be back. Not as it was. And why would you want to? To set right a 'wrong' that our ancestors from thousands of years ago committed in extinguishing the mammoth? It's a pretty specious argument to begin with. Humans were particularly rare back then; it's not likely we over-hunted mammoths. Dozens of megafauna like the mammoth went extinct around the same time. It's not coincidence. We didn't kill the mammoth, mastodon, giant beaver, ground sloth, sabre-toothed cat, American lion, short-faced bear, giant bison, etc. off. Probably not any of these species, let alone one.
