A DnD’esque system was introduced in Vailor, it quickly got shelved as it was hard to balance.
I don’t think RP combats drawback can be summed down to it having no objective metric, since that could also be considered one of the upsides to that style. In PvP, the outcome is black and white, there is a winner and a loser, meaning one party doesn’t have any character development in that scenerio. However in RP combat there doesn’t have to be a winner or a loser, which makes for better character development on both parties. The biggest reason RP combat is currently so bad, is because it is so time consuming and subject to potential powergaming (And horrible with many people, but we already know that, nobody disagrees with that).
I think the server has come far in acknowledging the problems of both systems, and have over many years found the system that make the least people angry (Not the most people satisfied). Personally I don’t really care what system we end up going with, I just want people to understand that the “roleplay” or character development of player personas, take priority over pixels in minecraft.
With a DnD’esque system, what you are essentially arguing for, is Roll-play?