I've been thinking of the whole "Ruling vs Rules" juxtaposition and I find it literally eye opening. OD&D was written with the idea that players would come up with ideas literally "outside the box." If a player wanted to play a dragon, the DM should work with the player to make it happen (assuming it fits the campaign I suspect.) Very open ended. The assumption is gaming group will make the game their own. The original Basic D&D Boxed Set kept to that feeling of openness.
AD&D was written with the idea of a set of rules for tournament play that would be in universal use (from the DMG Introduction):
I started with AD&D, and of course the first thing we did was houserule the shit out of it (we never called it houseruling). I don't think I ever read this passage until 30 years later. Still, as intended, the game was not meant to be tweaked to fit your home game and your players - the players were to conform to the rules.Thus, besides the systems, I have made every effort to give the reasoningand justification for the game. Of course the ultimate reason and justificationis a playable and interesting game, and how much rationalization canactually go into a fantasy game? There is some, at least, as you will see,for if the game is fantasy, there is a basis for much of what is containedherein, even though it be firmly grounded on worlds of make-believe. Andwhile there are no optionals for the major systems of ADVANCED D&D (foruniformity of rules and procedures from game to game, campaign to campaign,is stressed), there are plenty of areas where your own creativity andimagination are not bounded by the parameters of the game system.These are sections where only a few hints and suggestions are given, andthe rest left to the DM. (emphasis mine)
2e begat more rules and 3x even more. The idea that sufficient rules could negate the need for rulings meant that all DMs, if they were fluent with the rules, could, in theory, be created equal. All players would be on firm ground in organized play, as the rules in use would be consistent. I believe 4e moved even further in this direction, but I'm no expert, so I could easily be wrong.
5e seems to be a step back in the right direction, at least in part. Discretion is given to the DM to tweak the default rules to make things a better fit for his campaign and the players therein. If 5e grabbed any inspiration from the OSR, it is here. Not in the rules themselves, but in the flexibility of the rules.
Do you need to have all of your options spelled out? Height, weight, age - all determined randomly by dice and charts, like in 1e? Or can you just as easily decide those on your own? They don't effect the mechanics of the game, just the roleplay - and it seems like every edition after the White Box started putting more and more emphasis on roll over role and rules over rulings.
Maybe that's why I like the clones so much, as they tend to put more of the weight on rulings over rules.
Heck, even the current AD&D 1e campaign I'm playing in, which hues fairly close to being BTB, didn't have us randomly determine our age or physical stats. Which is right, even if the rules say it's wrong. No set of rules should need to define how you are going to roleplay your character beyond general class and race tendencies. If I want to play a portly and balding Tavern Keeper (Barliman Butterburr anyone?) I don't need rules telling me I'm short, thin and 18+ 1d4 years old.
Of course, I could just play myself, but where's the fun in that? ;)