I still don't get it. If you load such a ship with helis, it is good enough only for those knife fights with SE Asian countries. Against any country with a decent SAM system, such ships will be useless.
Given that, countries like Vietnam could easily counter by buying S300 from Russia.
No not really. Look at the entire system, not the only the platform. The correct question would be where does such a ship fit in within the PLAN's needs?
1. Amphibious capability: Right now, China's massive amphibious force currently consists of mostly LST's, which while being excellent force multipliers for the frontline Type 071 LPD's, don't have the legs to support operations more than 1000nm away from Chinese waters. Thus their role in reality ends with providing amphibious cover for China's many Islands and maritime territories (including Taiwan).
Considered in conjunction with the 28000ton full load Type 071 LPD's, such a force would provide a significant amphibious spearhead, providing a springboard from which thousands of PLAMC(People's Liberation Army Marine Corps) marines could be inserted into any theater within the Pacific and Indian Ocean. A task force of 1 circa 40000ton LHD and 2 28000 ton 071's could conceivably land and support more or less 2000 troops.
2. Humanitarian needs: A ship capable of operating and supporting 38 helicopters as well as landing craft/hovercraft anywhere along China's coast would be a massive humanitarian aid boost considering flood happy Pacific weather as well as the need to provide humanitarian aid to foreign countries within the Pacific and beyond.
3. ASW capability: Large LHD's are also massive ASW assets inherent of their ability to base large numbers of ASW helicopters which in turn, can clear a large area of unwanted submarines to open the way for other operations.
With this platform, the PLAN would have all the necessary components for far ocean amphibious operations as demonstrated by the ongoing Anglo-French Corsican Lion amphibious drills. An aircraft carrier, LHD's, multiple ocean going LPD's, ASW escorts, SSN escort, capable at sea replenishment support, area air defense destroyers for long range aircover and capable high speed ship-to-shore connectors(large carriage, long-range hovercraft).
But lets wait and see what the PLAN eventually commissions, or at least for a shipyard launch...