Mister Spock wrote:
With the advent of the Replicator, meat farming and the eating of real meat is probably no longer a necessary. However, much like the No Smoking sign seen in The Wrath of Khan, just because something is no longer necessary or strictly healthy, doesn't mean people won't still do it.
I once assumed everyone on Earth was essentially vegan since replicators became standard, but there are several times that humans eat real meat and animal products throughout the later series. It seems to go back to the idea that there is a subtle difference between replicated foods and 'real' food.