Most US Navy ships have had CIWS systems since the 70s and have had many upgrades to their tracking systems since then. The US Army adopted the LPWS (C-RAM) which is basically a portable CIWS for land use. (The Russian version of the CIWS is called a Kortik.)

It wouldn’t surprise me if there are already CIWS-type systems for commercial ships operating in hazardous zones.

I have had the pleasure of standing next to a few CIWS systems during live fire testing and it’s quite the experience.

So, Gary Brechner wrote an article about this, like 20 years ago: Basically, that the combination of expense to build, and vulnerability to specific asymmetric threats, that huge ocean-floating warships represent, means that in the long term they are doomed as a serious military platform. They should go on the shelf alongside that thing the Nazis did with trying to build small-building-sized tanks, as something that just doesn’t make sense when all factors are considered.

It might seem that the submarinization of the Black Sea fleet proves him out, but as it happens, I coincidentally got to talk recently to an actual military strategy expert on the topic and this was his take:

• Deterrence is a relevant factor. Lots of expensive military kit is pretty vulnerable. The issue is, if you do start taking steps to attack it, what’s going to happen to you in response. That’s at the heart of keeping a lot of big powers’ naval forces safe, more so than them being invulnerable. Real no-holds-barred war is pretty rare in the modern world; most military kit goes around most of the time being used for force projection or little proxy wars, usually not full-scale war against peer enemies.
• It may be that the big ships are becoming more vulnerable as time goes on, yes, but it’s not like that’s new. Once it does go past the level of “we don’t want to do that / provide weapons so our proxy can do that because we’re scared of the response,” and proceeds to a real fuck-'em-up war, losing big battleships and carriers at a shocking rate has been part of war since around World War 2. They’re hard as fuck to defend and navies tend to be super cautious with where they put them as a result, and once it comes to a real war, they start sinking yes. It’s not like land warfare; it only really takes one day where something goes wrong to sink billions and billions of dollars worth of your navy irrevocably. Adding a new way that that can happen doesn’t necessarily change the shape of the war because it was already happening and was already part of the calculus.

I think, as some other people have said, that most of it is bad strategy and tactics by the Russians, of putting their big naval assets within range of the weapons that can fuck them up and for some reason not reacting (until very recently) when as a result they started sinking like pebbles in a pond.