Well, on a basic level, I assume eating healthy is better, so you've got that. But on a deeper level, limiting yourself to non-meat-and-dairy foods may show that you lack a well-rounded appreciation for food and thus for the things that are enjoyable in life. I pretty much made that up just now, though.
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"God Hand is the ultimate expression of the joy of humanity, specifically the punching part of the joy of humanity."-Shigeru Miyamoto