So the real issue isn't even about MSQ leveling the player, but rather the boring slog of absolute nothingness the DT MSQ turned out to be.

Which, yes, you would be correct. However, I don't think lowering exp and telling people to do side content is the answer. Why should anyone have any faith in the side quests when the main story was so sloppily written? Can we really expect anything better from the side quests?