Why does MTA keep small "useless" stations in operation?

[R36 Combine Coach]

At NJT it always is the case to close a smaller station than retain it as a flag stop (minimal or no platform, with just a sign). I would prefer request only flag stops over dropping all service outright, as this would provide local service with flexibility..

[MCL1981]

These tiny stops are indeed flag stops on most trains. But it's moot because there is always someone.I don't recall ever skipping any of these stops because nobody needed the train to stop.