Okay, well maybe not save the whole world, but definitely help to save that one species. And biodiversity is a good thing.
My husband sent me this article about bison and craft beer. It covers several rationales for pairing of bison and craft beer from flavor to their shared history and promotes them as a "very sustainable, local, natural product which fits in well with craft brewers.”
The article says you should eat bison because it's good for you, it tastes great with beer, and its good for the environment. That's the theory at least. Keep in mind that at least some (maybe most) of why bison are "healthier" is that they are generally pasture finished. If you fed them like cattle in feedlots the meat would have more fat and a less favorable fatty acid profile.
I haven't done any fact checking on the claims made about the more bison as more environmentally friendly meat source. It makes sense that if you raise an animal in the conditions it evolved to live in it would work out better. If it worked for thousands of years without people it must be sustainable on some level, but whether or not we can mimic those conditions without missing something is another question.
I have another reason to eat bison. Eat them because there aren't that many of them. Slow Food's Ark of Taste Program is based on promoting the consumption of rare foods in order to ensure a market and encourage production. Yes, the American Plains Bison is one of the over 200 species in their catalog.
I did a little checking and there are about 194 cattle for every bison in America (assuming the article is right that there are 0.5 million or so bison in America and a cursory internet search finds 97 million-ish (96,669,000 according to a 2008 census if you want to get technical) cattle). Clearly that has something to do with the market for their meat.
I'm all for helping the little guy. Especially when he's so tasty. Oh, and the article is right. Bison really does go better with most craft beers than beef.