Exactly this. Meat is a huge source of nutrition. Even though in our modern western society, we might not "need" to eat meat, but it's a hearty, plentiful, accessible protein and fat that stores well and can be easily moved and replicated quickly. It's simply much more practical still to keep eating meat in much of the world. I'm not going to go into the arguments about our biology either, but I think it's safe to say that our bodies are also very finely tuned to eat and process organic (from organisms) meat and use it as fuel. Sure, you can feed your cat a vegan diet or whatever and replace all of the vitamins, but there is no denying that the more "natural" way would be to just eat the meat and be done with it.

Many of the arguments for veganism come alongside ideas for better animal welfare, but the two are not mutually exclusive. The only reason we don't eat grandma after she dies is because it's culturally unacceptable. We can apply more respect and reverence to meat production without stopping entirely or pretending that the benefits of eating meat don't exist.

Eating Grandma is actually a really good way to get parasites and prion diseases, so there's more to it than just cultural acceptability. The reason we don't risk parasites from farmed meat is because it's dewormed and treated and inspected and cleaned.

Also, culture is shaped by biology, our brains are wired to find meat delicious because it gives us the proteins we need to survive.