Sadly I've tried time and again to RP well, PK hard, and just do things I think would be entertaining for Imms. On one occasion I even got imm interaction (through an NPC) and a short term custom title for a sweet kill on a character I tried very hard to RP well on and got zero imm exp from it. Almost as if saying "yeah that was ok kid, but try harder."
The only time I've gotten Imm exp since I came back 6 or 8 months ago was on a throwaway character at very low level an NPC just started talking which turned into a very small quest and 100 imm exp. Better than nothing ever, but pretty disappointing for it to happen that way.
I remember during my first bout of playing this game (only about 5 years ago) the population was about double what it is now but I remember several key instances of getting imm exp over a pretty short time.