[derefr]

Because—as half the threads above say, if you'd care to read them—animal farming is very bad for the environment. It's not about the ethics; it's about how much pollution it generates to create the fertilizer and the pesticide to grow the grass or grain that we feed the animals, and about the methane the animals release during their lives—beef-cattle methane, by itself, is 16% of (indirectly-)anthropogenic greenhouse emissions.

Lab-grown meat isn't important because it's "cruelty-free"; it's important because it's possible to make it far, far cheaper in externalities (and, hopefully, in real dollar-value costs as well) than the alternative. That means more people fed balanced diets per carbon-dollar.