Still pretty common at least in places near where oysters are grown, I think. My guess would be also that tastes changed over time as oyster fisheries were overfished and/or polluted by growing cities. There have been numerous waves of oyster collapse on the US east coast over hundreds of years, and places that once had them in incredible abundance now have none (though efforts to restore them have emerged).

There are a variety of parallels in the history of overfishing where a given seafood that was once abundant was then seen as undesirable and served to servants or prisoners (lobster, salmon), but today is somewhat of an expensive delicacy.