I eat lots of meat because I can and because it's healthier then the alternative. Our bodies are too good at converting sugars and starches into fat and food is so available that we need less effective calorie source not more. Meat is a great food source because it's both filling and were not all that good at converting it so we really need to be eating more meat we just need to figure out a more effective way to produce it. For me the climate change argument is easily overcome by the health benefits of a high protein diet. There is lots of data out there linking high starch and grain diets to obesity and diabetes. So there really needs to be better alternatives before we can reduce our meat consumption.
Protein is easily replaceable by things such as beans, yogurt, tofu, dairy, and more. Unless you have other dietary restrictions it's not very hard to avoid protein deficiencies. Eating less meat or no meat doesn't mean eat more grains and starch, there is a lot of food out there and a lot of ways to have a diverse diet. Saying I eat meat because I can and don't care about the environmental impact is incredibly selfish. Regarding eating meat being patently healthier, that's not necessarily true either.
Was about to say the same. You do have to worry a little more with plant/legume based proteins about mixing and matching complementary proteins to make sure you're getting all the essential amino acids that you'd otherwise get from a serving of meat, which is considered a complete protein. That said, it's still relatively easy to do. On that note, re snoodog's comment- suggesting that we're not good at converting animal protein to useable energy/nutrients, and thus should consume more animal protein, is flat out wrong. If anything, we should be eating way less animal protein than we currently do in the west, given that we're more equipped to derive sufficient protein and nutrients from small amounts of meat without taking on the risks related to high fat/cholesterol intake that come with consuming large portions of the same. Last I checked, there have also been a series of studies linking high intake of certain meats with increased risk of certain cancers. Think red meat is still linked to gut cancers, and a recent study suggested that consuming a given amount of processed meat (eg bacon, sausage, salami, baloney, etc) presents a cancer risk akin to smoking cigarettes. Discard the environmental argument if you will (although I don't really understand why you would), but don't assume that more meat = better lifestyle. Current data doesn't support it, and basic nutrition supports the opposite.