Not only has the mission profile expanded, but the potential threat environment has grown to include orbital and hypersonic weapons that might be fired well beyond the former threat envelops. Also, many weapons they will face may have terminal maneuverability making them much more difficult to destroy. As you layer on each new threat you have two choices; make the ship bigger to hold more defenses, or make it smaller so it will be a more difficult target. I’m guessing the Navy will go with the former.
If the role was merely to defend ownship, sure, make it smaller and more maneuverable with a low cross section and robust self defense capacity. But the mission of these ships is to defend the battle group and/or other designated assets. Can't make the carriers smaller realistically. So either more defenders or more capable defenders are called for,