Earlier quoted context omitted.
People crave sugar, nicotine, narcotics, and other things that aren't good for them, so your argument falls apart there. You crave meat for a variety of psychological and physiological reasons, but not necessarily because you're missing something that meat provides. My argument for not eating meat is simple - why kill something for food if I don't have to?
So as I said above, there's a certain degree of actual feedback in terms of your body "Wanting" foods that contain proper nutrients, and while with a combination of multiple types of beans, supplements, and other foods you can approximate some of the proteins you'd be missing out on by not eating meat, it's both far more complicated (and until recently in my life, expensive), and as my initial statement about a lack…
I've been a vegetarian for 15 years or so, and would question your statement that finding non-meat protein alternatives is complicated.
It sounds like you're trying to make an argument that not eating meat could have long-term health hazards, in which case I'd argue that it's easier to prove that meat is bad for you than it is to prove not-eating it is.