I really don't follow how a smaller ship would require a bigger launch and recovery mechanism for the same VDS as larger ships.
With smaller ships, where space is at a greater premium, you would want the most compact variants you can get for them, whereas it is typically the larger ships, with more space available, that tend to have the bigger and more elaborate versions of equipment, which usually also has greater range/functionality as well.
As for dedicated mine hunters vs LCS, well the dedicated mine hunters can no doubt do a more comprehensive job, and there would be need for them later, but would they have the same reaction speed and survivability as an 056?
I can see the PLAN using 056 minesweepers as a first wave force that clears a path through enemy minefields fast, and potentially where the battlespace has not been entirely cleared of enemy surface and air assets.
The 056 would be better suited to holding their own against any enemy fast attack craft that slips through and should be able to fend off small scale, opportunist air attacks as well. Something dedicated minesweepers are unlikely to be able to do.
In addition, a minesweeping 056 would present as a far less obvious target to the enemy, especially if they are operating alongside other regular 056s, so it would far harder for an enemy to specifically target them to presurve their minefields for as long as possible as they could potentially do against dedicate minesweepers.
If the PLAN as anything similar to the AN/WLD-1, the 056 could deploy it within minutes, and then steam off to perform other duties while the USV goes off and maps the minefield independently.
In this way, the PLAN can get detailed maps of the enemy mine field without alerting the enemy that they are mapping the minefields, while performing other duties, such as hunting down enemy FACs, at the same time.
With that knowledge, the PLAN can choose where and when it wants to clear a path through the enemy minefield and deploy its dedicated minesweepers then, and potentially clear a path far quicker than the enemy would expect and achieve tactical surprise and advantage.
The same USV could also be used for ASW, so instead of hunting for mines, they would form a patrol parameter to guard against enemy subs trying to sneak past to attack valuable targets.
I think USVs will take off in a big way similar to how UAVs are reshaping air forces, so giving the 056s a means to deploy and recover USVs would be a very good investment and a cost effective means of futureproofing the class.
In a similar vain, I think that the PLAN will find its LPDs and future LHDs to be useful as mobile motherships for a whole host of USVs that it could then deploy long distances with a task group. So don't be surprised if LPDs and LHDs become a standard component of future PLAN carrier and other expeditionary task groups.