It may strike people as funny, but for all my obvious joy in systemizing things like character classes and spell types, I have a deep distrust of game systems, as you can see lingering in the discussion of bonuses and penalties deep within the previous post.The key to eliminating this paradox is to distinguish between a focus on system and a focus on the product of a system.
The general goal of rules in an RPG is to make things happen in a fictional world. This is true in the most direct sense of conflict resolution -- what happens next in a battle or challenge -- but it's also visible in the fringes of the system, in rolls to determine whether a group of bandits includes a magic-user, for example.
The problem, however, is that sometimes people get distracted by the rules that create the fictional events, instead of focusing on the events themselves. And it's my observation that some kinds of rules are more distracting than others. I mentioned in the binary effects post that I don't like too many distinct bonus or penalty types because they require more time to look up details, but that's actually not the main reason I dislike them; it's because making some things worth 1 point, others 2 points, and a few 3 points lures players into considering their best numeric option. It distracts players from the fictional world.
It's also why I prefer the older "hard" armor classes to the more modern approach; to my way of thinking, you should start by defining the broad classes of armor in the fictional world, then assign numbers if necessary, rather than focusing on the numbers and figuring out which combos of equipment will get you the best numbers. It's why I prefer the OD&D ACs to the AD&D ACs, why I prefer descending ACs to ascending ACs, why I don't allow negative armor classes, and why bonuses don't stack when I run games. And, of course, it's why I prefer 1d6 damage for all weapons and distinguishing weapons by what they do instead of what their numbers are.
Sometimes, it gets tricky. The vancian magic approach usually includes spell levels, which can occasionally get people focused on numbers instead of the non-numeric descriptions of what the spells do. However, the chief non-vancian spell system, spell points, gets even more bogged down in numbers: casting costs and maintenance costs, in TFT or GURPS, for example. (Plus the non-numeric but very system-focused concept of spell trees or prerequisites.)
The distinction between "old school" and "new school" means a great many things to many people, but one of the main things it means to me is a distinction between "focus on the fictional world" and "focus on the system". In that sense, there were "new school" games practically from the very beginning, and there are even seeds of system worship in OD&D itself.