Originally Posted by Afrobean
He had no reason to during much of the series after the core 7 all knew who he was but before they expanded in Unlimited. He just wore the mask because the mask is iconic to who "Batman" is. In movies though... well, actors seem to always be running around without their iconic masks on. I'm sure they wouldn't rob us of the cowl completely, and Batman would be involved directly in at least one action sequence, I'm sure, but I bet he could spend the whole movie in his Batsuit but only occasionally putting the actual mask on when needed.
I don't know if they made the choice to always have his cowl on around the JL because it looks cool, or because of his distrust towards metahumans.
I lean towards the latter, but who knows. He always took the cowl off in the Batcave, but never at JL HQ which says a lot.