With the Romans passage - in context, it's not condemning vegetarianism qua vegetarianism. The "meat" referred to was meat that had previously been offered to idols. Some Christians were like "Eh, meat's meat, idols have no power, everything belongs to God, we're free to eat it if we want" - a mature spiritual attitude - while others were like "OHNOES, that's evil idol meat!" and wouldn't touch it. Paul's point was that the latter Christians would be sinning if they ate that meat, given that they thought they shouldn't; so mature Christians should not try to tempt them into eating it. But nor should the non-meat-eaters tell the mature Christians that they were sinning by eating what was, after all, perfectly ordinary meat. So the passage isn't really about vegetarianism at all.
I think it's impossible to reconcile a Christian worldview with a vegan worldview - ie, the idea that eating/using animals is inherently immoral (often, though not always, combined with the idea that putting humans above animals is "speciesism"). God gave Noah and his descendents permission to eat meat after the Flood - I wouldn't go so far as to call it a command to eat meat, but He certainly said it was OK. But I think there's no problem at all with Christians choosing vegetarianism or even strict vegetarianism (practically equivalent to veganism, but coming from a different philosophical position) - whether for health reasons, concerns about animal cruelty, budget reasons or whatever. In fact, I think it's pretty difficult to reconcile Christianity with factory farming. Just think what an impact all the Christians in the USA could have if they refused to buy CAFO meat!