If we're talking Final Crisis, Superman got his own important side story but he didn't take over the whole event.
An event where the main thing anyone talked about was still Batman shooting Darkseid. And it also helps that Morrison is a better writer than Snyder, plus Superman and Wonder Woman are designed to be at the center of all these larger than life things. Batman doing it just comes across as epically stupid. It's outside his wheelhouse and the genres and tropes that make him appealing.