I'm not sure what you mean by saying our digestive system is designed to eat meat. Are you trying to say we're carnivores? We aren't, we're omnivores. If we were carnivores we would have a much shorter digestive track and no grinding teeth. Our long digestive track and grinding teeth are specifically designed to get nutrition from fruits and grains. (Yes, grains. Despite what you've said we have evolved to consume grains, hence the teeth we have etc.) We also need proteins, such as meat, to be healthy. You are correct that what we need is a balance of nutrients to be healthy. Meats can be a part of that, but too much meat isn't good for us any more than too many sweets (aka carbohydrates.)
If this experiment works out, it at least would give us a way to create meat that is healthier for us, without all the antibiotics that current methods seem to prefer.