UngeheuerLich
Legend
I know that is sarcasm, but to a certain extend this is true.Ahh yes, as we all know the best rules are a blank piece of paper so the DM can do whatever they want!
The move from theater of the mind to battlemaps codified certain rules.
So instead of describing how you duck behind cover and the DM gives you an ad hoc 9/10th cover bonus the resolution changes to looking at the battlemap and drawing lines from one square to the other. Which is time consuming. Which is assuming the battlemap depicts the given situation 1:1. Which ignores that envitoment is 3d and that a character take on different poses to adapt to the cover and so on.
So having less codified rules is an advantage, as long as the DM adjucates fairly.
Probably the fairness was lost and the game became less cooperational between players and DMs for a while so codified rules were needed.