I don't understand this argument.
half of them aren't optimized for Z-20 - sure, but 054B still doesn't exist at all. Half(and counting) is well over 0.
If 054B is intent on being used with the fleet - it will almost certainly be using the same combination, too. Through IEPS - sure, but that's just a sign of a newer ship.
They're mainline surface combatants. Their job is to shoot at everything within reach, and to under no circumstances let something pass past them. This "past them" is especially crucial since any hypothetical "listeners" tend to operate to the sides of the formation(no physical barrier), and 055 can be expected to be either far forward (positioned for strike) or behind(ABM), unless of course your whole screen isn't composed of them.
So being b/n the carrier and the threat (physically, too, if the situation calls for it) is exactly a 052D job - there is no one else to do it. This obviously includes submarine threats, or what's the point...