I never bought the idea that the Feds was a truly "egalitarian" society. Example: you can't simply enroll into Starfleet or the Vulcan Science Academy without taking some sort of test. Way I see it, you get access to the basics: food, shelter, clothing, a stipend and education. But, if you want more, or something "exotic", that's what a stipend is for (especially when dealing with non-Federation members, like the Ferengi).
As for Starfleet replicators: I figure that the more sophisticated the machine, the better the taste of the food. You can get a "basic" meal consisting of bright cubes (with each different color representing a protein, a carb, a fat, etc.), good for one's dietary needs, or you can get the full sensation of actually having a meal that actually looks like a meal. And if that is the case, maybe the incentive to do well in Starfleet is to strive for those better replicators?