Unbelievably, there appears to be some debate over the wisdom of cloning mammoths from recovered DNA. Wisdom doesn't come into it. The question to ask is not, "Is that really wise, sir?". The question is, "would this, or would it not, be totally awesome"? Less of the John Le Mesurier, more of the Bill and Ted.
I mean, dammit, the things will pay for themselves. Even assuming that I don't get to use one to commute to work (totally awesome), just imagine the money you can make from thrill-seeking big-game hunters. Never mind the mighty hippo - this is real game. More so if you rock it old school and take it down using only stone axes and spiked pits. I can imagine no finer achievement for 21st century science than to clone an extinct species, and then kill it.
Plus, has anyone run the numbers on the efficiency of farming megafauna? OK, more food and water per head, but if you can kit out a big enough abattoir your processing costs per carcass should plummet, surely. And there's a hell of a lot of meat on those things.
But of course, the practicalities are missing the point. "Physics is like sex. Sure, it may give some practical results, but that's not why we do it" We should do this because we can. We should do it to show just how much we can do. Extinct species made to live again. And people say science doesn't have all the answers? If you don't want "let's go mammoth riding" to be the answer, then you are asking the wrong question.