It sounds low but even with our current poor diets the average person actually gets too much protein.
Only two things are wrong with vegetables...
1) Incomplete proteins mean that you need to eat at least two types as opposed to one slab of meat
2) B12 comes from the soil but as we steralize our food now you have to get this from dairy at the minimum
Every other vitamin and mineral can be got with vegetables, meat was simply an advantage when we were unable to import vegetables from around the world.