Because vegans are ignorant morons.
If you are ACTUALLY STUPID enough to contradict nature's plan for life, then... That's self-explanitory.
I like how you gave me an answer that... wasn't so much of an answer, as is was meant to be some sort of insult.
If you really wan't to talk about contradicting nature's plan of life, then how about all of the other rules that we've broken? Like taking a dump into a sewer system that leads into the ocean, rather than in the ground. Or driving cars rather than walking. Were those not intended? And how about digging up oil and valuable materials from the ground. Surely that doesn't contradict natures plan for life either. There's also the use of electricity, flying, science, space exploration, sitting on your ass hours a day in front of the TV or computer while getting fat rather than making use of yourself, grocery shopping instead of hunting. The list just goes on...