I think it is important to note the Federation previously wasn’t in the business of building warships. They are so technically advanced, they didn’t need them.

As a friend of mine put it:

Everyone’s best warships are in a dead heat with a luxury liner full of nerds that happens to have guns on it.

Starfleet ships didn’t need armor. Their materials science was already so advanced, they had to use structural integrity and dampening fields to push beyond what existing physical materials could accomplish.

So when they roll out an actual warship using physical armor plating, it is an incredible advancement in materials beyond “simple” energy-reinforced hulls.

Alternatively, it’s really boring technology but the idea of a Starfleet warship is so new they are salivating over things everyone else has been using for centuries. It’s like giving a tank to a soccer mom and telling her to have fun in traffic.