My take is that it's probably the mess and the smell. I know I feel slightly guilty taking chinese food, pizza, or cinnamon rolls onboard a plane because others have to smell it.

I'd also guess that the CRCs were originally set up around the 'lounge' concept. In other words, it's a bar, not a restaurant. Indeed, just about the only way to justify the cost for most is to assume that the free drinks will pay for the cost of the membership. Unfortunately, I don't drink, so I have to admit that I do it because I can afford to blow the money for the luxury factor.