Akvan,
I would think if vegetarianism is indoctrinated as a tenet in Buddhism, it would inevitably create unnecessary burden on some followers. By insisting on vegetarian food, not only is one attached to a certain kind of view, the act itself is also unwholesome. Not forgetting that it is also impractical to sustain on a long term basis. We can only trust the Buddha had arrived at the best compromise by accepting whatever food that was offered to the Sangha by His followers.