None of the differences you mentioned deserves a new digit. One of the many example is J-7 produced from 1965 to 2013 with much more letters, more missile and radar upgrades, yet it was always J-7. It can not be compared with the jump to J-10.052D is vastly different than 052C. There's a 10 years gap between them. One is limited VLS + slanted launchers, the other is full VLS.
This is the PLA rule, not yours or mine. The basic rule in PLAN for a new digit/type is the basic design architecture of hull plus power-plant. 052C and D are of the same hull and power-plant, any other changes are just upgrade no matter how vast you perceive.
However, you could be right IF 004 simply means ship number 4 instead of type 004.