The Sensors and in the future weapons on these ships would not be feasible on a much smaller ship. This is why even a modern frigate is the size of a destroyer

The Sensors and in the future weapons on these ships would not be feasible on a much smaller ship. This is why even a modern frigate is the size of a destroyer from a few decades ago. Also, the Zumwalt which is a larger ship overall has about half the crew of previous generation destroyers.