I eat tons of vegetables, legumes, grains, mushrooms, etc. I get about 3000 calories daily, about 15% of which are from protein (more if I eat lots of beans or use soy flour, etc), and plenty of essential fatty acids from avocados, olives, etc.
I already addressed the "why not eat untaxed meat" issue above - it's psychologically easier to quit it all at once, without teasing yourself. Only then your body eventually adjusts, you stop craving meat, and your brain regains the ability to recognize how great vegetables taste.