Arguments based on creating demand are weak. Just living in your house requires land clearing that inevitably requires killing, what to speak of eating vegetables clothing and all the other stuff one consumes just to stay alive.
Arguments on whether it is ok to be non-vegetarian or not have gone on for ages. Because it is such a grey area, the Buddha's advice on the issue is brilliant. One is responsible for one's own actions only, i.e not killing, not directing someone to kill and avoiding meat that one knows was killed for oneself. All other meat is permissible. There are consequences on health and environment, no doubt, but it is karmically neutral. So when if a person asks what's wrong with eating meat, it may be wrong for many reasons, but not for karmic or ethical reasons.