LDoN experience was always less than par. Sony considered the LDoN points and chests to be part of the reward, so EXP is nerfed in LDoN. This isn't to say it's lower than when it was released, just that it was released lower.
This said, LDoN's often been good EXP for me. Despite lower EXP per MOB kill, I've almost always been able to get single pulls, easy MOBs, some points for fun and the upgrading charm aug was neat.. but, most importantly, I could just go to PoK, round up a group, and get in one in under ten minutes, then either redo and replace or call it a morning/afternoon/evening/night/some-time-I-should've-really-been-in-bed-much-like-right-now. Since groups were abundant, and I could create/find groups and use the time I did have for EXPing, for, well, EXPing!
And, hey. When you complete a "Hard" LDoN in under thirty minutes with cheaply-geared players, it's an ego boast. (And, yeah, getting owned by the a curse that the group noob opened while you're fighting a mispulled train was something of an ego pot hole.)