Literrally every navies have been based on a "three tier structure". There's nothing special from China about this topic.
Isn't the Type 054A good enough for ASW ? Also the development of a carrier fleet and extended anti-submarine air assets have greatly improved the Chinese capabilities in this regard.
Comparing with other navies the Chinese may want to keep the three tier structure simply because of cost concerns.
One of the main issues China has is lack of anti-submarine warfare capabilities. A new frigate class which is dedicated to the role would go a long way in addressing this.
China's maritime geography is simply too militarily disadvantageous so it must always maintain a numerically large "garrison" force to secure the seas within the 1st island chain, they also need a significant "forward defense" force if they want to contend the seas between the 1st and 2nd island chains in order to truly secure the seas within the 1st island chain. In order to do so economically it makes sense for them to have a near seas hi-lo and far seas hi-lo ship types.
It may eventually make sense to combine the near-hi and far-lo ship types into a single one if China sees a higher threat environment and is willing to invest more in such a capability. AA and missile defense needs will be primary drivers for such an investment. The carriers and AA surface combatants would be more equal escorts for each other rather than necessarily the latter escorting the former.
Let's continue the discussion here
https://www.sinodefenceforum.com/plan-surface-combatants-2020.t8082/page-3#post-553958