The reason of me going Vegan is mostly ethical, but many people go vegan for health purposes. It leads to an impression that vegan people try to lower their protein consumption and calorie intake. This is not true at all. Vegan diet is simply seeking all the nutrients from plants instead of animal meats.
Protein has been the biggest concern for meat-eaters. Protein is made up with different amino acid and originally it has been found in plants. Meat protein is like second-hand protein; herbivore, like cows and goat, consumes plant-based diet and converts those plant protein into meat protein. We actually have all the enzyme needed to digest plant-based protein, and in contrary, have a harder time to digest meat protein instead. It's way better to consume protein directly from source.