PLAN already has the capability of attack helicopter storms with their four 071s, each providing battalion-strength Marine landings. I'm not sure if a LHD without jump jets gives PLAN more capability than two additional 071 LPDs.
LHDs carry many more troops.
LHDs have a larger craft (both water and air) carrying capacity with much larger hanger space for upkeep of more aircraft.
LHDs typically have larger and much more functional command spaces, hospital facilities, etc.
If the Chinese foresee any need for large amphibious operations, or very large humanitarian capabilities, LHDs makes sense.
Otherwise, they can certainly double up on LPDs.
I expect the PLAN is going to do both.