To some extent it is. Very few purely vegetarian communities have existed in human history, AFAIK. However, as you imply, large numbers of human beings live a healthy vegetarian life (I would estimate a 100 million or more, just in India), and the argument that meat is a necessity, generally speaking, does not seem to hold much water.
You are quite on target I think w.r.t the opportunistic use of Cartesian doubt. Ignoring the revealing attempts at humour here on the list, there are some serious arguments that have been offered against many of the positions of animal rights/welfare. A while ago I posted something from Bernard Williams here on LBO. I will try to find it again on the Internets.
--ravi
-- Support something better than yourself ;-) PeTA => http://peta.org/ Greenpeace => http://greenpeace.org/ If you have nothing better to read: http://platosbeard.org/