Might be a bit over-eager; it's a subsonic sea-skimmer with a 130kg warhead. Potent, but there has been 60 years of defensive development against exactly such threats. Deploying a slightly stealthier Harpoon in the 2020s is underwhelming.
Depends on what the detection range is for the NSM. If it can get halfway from the horizon to the target undetected, that's a big deal. Crud, even if you can detect it at the horizon, if it's not detectable by AEW or look-down radars on fighters there's not much the ships can do about it.
By this point of the anti-ship / defensive spiral any AShM should be doing at least Mach 2 terminal with deployable countermeasures. NSM for example will be in the PLAN's CIWS engagement zone for at least four seconds; that's over 300 chances of a hit per gun.
Sure, but it's also skipping engagements from longer ranged weapons entirely.
For sake of example, I'm calling the horizon/detection range 20km and I'm going to use USN weapons because I'm more familiar with them. Replace with the appropriate systems.
A ship would detect a subsonic missile 60 seconds to impact.
Shoot SM2, NSM is 19km at launch, 57sec to impact. SM2 at low altitude does about 1km/s. First interception chance happens at about 15km, NSM is 45sec to impact.
Shoot ESSM, which also does about 1km/s at low altitude. Second interception chance at 10km, NSM is 30 seconds to impact.
Shoot RAM, which IIRC does about 1km/s. Third interception chance at about 5km because RAM takes several seconds to spin up.
Shoot CIWS starting at about 3km and 10sec to impact.
What happens when the detection range of NSM is 10km? All of a sudden, you only have RAM and CIWS to shoot in your defense.
South Korea, Taiwan and Japan all realise this - so why don't other countries? Or i it just a focus on cost?
AShMs have not really been a priority in the USN.
At all. "We have carrier air for that."
And it's why I have been obscenely jealous of Kalibr missiles with their 1km/s terminal sprint for some 30km.