Read the entire suggestion, it's not only about getting experience by killing other players (Which was already refused, yes).
It was suggested many times.Answer: No.Just search it on forum.Getting XP for PK... obviously abuse.
Level divided by 2 (rounded down) equals how many times a RL day your character can lose experience points.Losing levels should be allowed or else level 21 will not care anyway. % of experience points lost could be indeed just your level. So a level 18 player would not walk around so carelessly shooting shit for laughs, while a level one can die all the time without penalty.