It is all about convention. A modern destroyer packs more punch than a WWII cruiser. Japan even calls her LHD a destroyer. Chinese call their corvette "light frigate". Since I am an English speaking world, I just use whatever terms they use.
The same for Japanese maritime terminology convention. We have:
- Helicopter Destroyer (light carrier)
- Guided Missile Destroyer
- Destroyer
- Light Destroyer (Frigate)
- Destroyer Escort (Corvette)
- Auxilliary ships
It seems that the JMSDF retains the convention terminology of the IJN [Imperial Japanese Navy]; the PLAN retains the convention of the INGQ [Imperial Navy of Great Qing].
The reason we use it is for historical continuity, or legacy component aspect.
It is all about convention. A modern destroyer packs more punch than a WWII cruiser. Japan even calls her LHD a destroyer. Chinese call their corvette "light frigate". Since I am an English speaking world, I just use whatever terms they use.
Also it is their largest surface ship, a good development for them.