These ships were commissioned to counter shallow-water adversaries. Iranian speedboats, pirates, et cetera. In the context of balancing Russia and China, they’re underpowered.
The orientation shift from terrorists and regional powers to countering a regional hegemon and emerging superpower explains part of the lifespan. The rest is it being a garbage ship.
That thing is a tri-hull: not your usual armoured ship. That is designed for speed, it is designed to plane and not displace (think speed boat but a lot bigger). It is described as "littoral" which is Latin for around the shore. It's got trendy slopey sides so slightly stealthy and also those angles will help in slightly deflecting kinetic incoming nasties.
So we have a weapon platform that can move really fast close to shore.
When you are running something as big as a national cough defensive cough thingie, you will have many experiments running in peacetime. Note the word peacetime. These experiments will cost billions of ickies (pick your currency - it doesn't matter.) This ship class is pretty obviously one such experiment.
You also have to remember it takes a very long time to get from "we need this" to the thing floating in the water or flying or breaking down on Salisbury Plain. In wartime, timescales are shortened. In (lol) peacetime it takes longer. For example in 1940s Britain, if you need a fighter/bomber which has decent firepower and a small bomb load and have a fair range and be bloody fast then you suddenly get the Mosquitto: https://en.wikipedia.org/wiki/De_Havilland_Mosquito . It was made of wood and was also considered two kills if one was shot down - that's how bad the Mossie looked to the Germans.
Any bit of war gear - ship, plane, rifle, grenade etc takes ages to go from plan to usage. Some become classics for example the AK47.
The other thing to consider is that people are employed to conceive, design and build these things. The US is a bunch of states and sometimes politicians ensure local jobs are secured for federal reasons/concerns.
No modern warship carries much armor. It's too heavy. And a sloped side will do precisely nothing to deflect incoming missiles.
I am personally surprised they’re giving up on the Littoral ships before they gave up on the Zumwalt class, the destroyers that don’t even have any ammunition for their main guns.
>It’s been used as a testbed for mission package development and leaving the fleet well ahead of its expected 25-year service life.
The US Navy is already well into a new project to develop a new guided-missile frigate [FFG(X)] to replace these LCS ships.