I think PLAN just don't see it wise to invest in anti-sub capabilities as nowdays conventional sub and SSN are hard to deter even by the most advance sonar. When electric sub operating in silent mode by travelling in slow speed making it even more difficult as demonstrated by NATO war exercise and recent Song stalking US CVN
Thats no exuse, and the reports of SSKs effiency is even bigger reason to start paying attention to it. ASW is not some minor role which you can utterly ignore, it's the key element of naval warware since the introducting of submarines. ASW operations are complicated and requires alot from all aspects of your fleet and the overall ASW cabapility pretty much sums up your navy's change to survive in modern naval warfare. The fact that modern subs are becomming more silent and capaple is not the reason to stop investing on ASW, doing so would be ridicilous. It's like trowing your hands up and say "I surrender". Should chinese airdefence just rest and quit for the day when their current systems are unable to properly detect new shtealth planes?
PLAN with plenty of sub will compensate lack of anti-sub capabilties by having sub escorting the fleet as having the both attack option and defense option. Yes,it is not the most effective. But i believe this is the present doctrine of PLAN with regards to build up. The most economical way to upgrade yr ASW is to build more sub as PLAN do not want to divine additional resources from sub build up
Concerating the ASW abilities to just subs is not the solution, it's as effective if your only way to destroy a enemy tank is using ATGMs. If the subs are your only ASW assets, it narrows your fleets overall efficiency to very minium. Using only subs means your ASW ability is limited to the coastal work and to small escort. It's like having only point-defence airdefence systems, but no multi-layer long range fleet defence.
To become a bluewater navy is sum of many things and if one element is lacking, the whole ability is lost or in this case not gained. If china wishes ever to grew from small naval player to the big boys league, it should start paying attention to it's defaults, which I'm sure it is doing. The fact that the overall ASw cabability of PLAN is still weak is that the whole prosess is still at it's starting point. China needs to developt new and more powerfull sonarsystems which is not an easy task when starting to build it from the scrats. It needs to incorporate these new sonars to operational use, and that requires completely new doctrines and operational methods. Training to do that takes time and at the moment these projects are not even ready.
With sonars you can only listen and detect the enemy subs, then you need to destroy them. China needs to field workable modern ASW weapon system (missile system would be good) which needs to be adjusted to the new future sonar systems, but also with the main ASW helicopter in use...
There is still long way to china to walk (or swim
) before it's fleet modernisation is complete.