That is an important point. In essense, it appears to be a cultural thing. Ie: the majority of humans in the Federation (and according to Enterprise, which, like it or not, is still canon... they got this idea from the Vulcans, who are vegetarians) feel its more "enlightened" and "moral" to do it that way.That's not entirely true. Remember that Miles O'Brien's mother cooked real meat like mutton shanks. Keiko was somewhat revolted at the thought of Miles' mother actually touching and handling "real meat".
It's apparently not a common practice, but it still exists.
But just like in a society where everybody is conforming to a certain way of living, there are always a few who rebel, either loudly or quietly. O'Brien seems to be one of them.
And yes, I know there are examples of "non-replicated" food as well, when Sisko goes home to meet his father, and when Picard goes to meet his brother's family, both offer him "home cooked" food.
I always assumed that replicated food would only be for Starfleet ships, for convenience (carry a load of raw biomass for use as any food you want, verses a load of food that might would take energy to keep from spoiling, and preparation time, etc.) But maybe indoctrination is so high that Starfleet types have a hard time breaking out of the mold.
But, when you get down to it, eating non-seafood "meat" is considered taboo in Federation society. Its another nice way to point out their moral hypocrisy.