RationalFrummie, that’s completely different, because he was directly disobeying G-d, while vegetarians are not violating any mitzvah (though, as I mentioned earlier in this thread, there are certainly some hashkafic dangers).
The idea that people should never be vegetarian because they should focus on people soon is not a valid objection. First, it’s not a zero-sum game, as becoming vegetarian does not mean one cannot also increase one’s compassion toward other people. Second, once you’re used to being vegetarian it takes no extra effort. So it’s not as if they’re taking time away from acts of kindness toward people. Third, there are many stories of tzaddikim going out of their way to save animals or prevent their suffering. Exerting oneself for the benefit of animals is not forbidden — to the contrary, we learn from these stories that it is praiseworthy. Finally, many people report increased energy and health (and the evidence shows that vegetarians live longer and are far less likely to die of heart disease and many cancers as well), so they might actually be able to engage in more kindness toward people than non-vegetarians do.
DY: Meat is not required as oneg Shabbos, and many vegetarians find that can find other foods that they receive just as much, or more, pleasure from than meat. Since the Torah says we can eat meat if we desire it, then it makes sense for people not to eat it if they don’t desire it, or feel that they have some good reason not to eat it.