You are probably aware of the dichotomy “rules vs ruling” in rpg. Simply put, a rule is a specific way to adjudicate a situation in play that is meant to be enforced every time (usually written in an official rulebook) while a ruling is a decision a GM make to adjudicate a specific situation. A good ruling take into account the rules, the specifics of the situation and common sense. Both can adjudicate a situation through a dice roll or give a definitive answer. For example, in D&D 3.5, there is a rule saying that being prone gives you +4 to AC against ranged attack. In another game, a GM could decide that (say) the kobolds are not very proficient with their bows, so that a prone PC would be hit by their arrows only 50% of the time. Per the rule, every time a PC is prone, they should get +4 AC, but the ruling may be different next time against other foes (altough a GM may use it a bit like jurisprudence).
I’m pretty sure that I’m a “rule lawyer” : if we play a game and there exist a rule, I like to know about it and I want to make sure the table knows about it when it should be used in the situation at hand. As a player, I don’t like it if the GM break it without very good reasons (even if it’s in my advantage) : it often feels cheap and unless it’s clear the rule should not apply in the situation, it also feels like cheating. As a GM, I hate making a ruling superseding a rule. I used to be the guy at the table that could quote most rules in D&D 3.x, and that could find it in seconds because I knew the rulebook so well, so it was not that bad, but every time I was unsure, I would double-check. I’m all for house-rules and dropping rules that don’t work. But dropping a rule means that the rule is not in play, not now, not ever; it does not mean it’s not in play right now, but may be next time a similar situation arise. Bottom line : if there is a rule in play, I want to use it consistently, and not using it when it’s more convenient (for the sake of the story or book-keeping or whatever) makes the game less fun for me.
Sounds like fun to you? Me neither. That’s why I don’t master rules-heavy games anymore. Learning the rules in the first place, halt the flow of the game to flip through a book to know what modifier to apply in the situation, prepping NPCs and monsters that needs lots of stats, running a combat encounter with different creatures and spellcasters (using different spells that each have a specific entry)… That’s way too much work for me, and it makes improvisation at the table very difficult. And improvisation is essential to run a good rpg session : that’s where all the magic happens.
But rulings can devolve into pure GM fiat, where the players are never sure of their odds of success. So a robust ruleset is very important to give structure and references for rulings. I think DW does that very well, but the d20 system can be perfectly suited to that. Remove all the specific modifiers, strip everything down to the ladder of DC difficulty (I don’t have my books near, but something like 10 is routine, 15 is challenging, 20 is hard, etc.) and some general modifiers (+2 for a big advantage, +5 for a huge one or something like that), then roll with it. Solid ruleset that a DM can use to make rulings in seconds that will still be overall pretty consistent, all without needing to check the book over and over again.
For a rule-lawyer like me, it’s the dream : following the rule is simple, so there’s rarely a reason to not follow it.