One thing about the design philosophy that caught my attention in a good way, however, was the very simple way WotC explained how they developed the rules:
- Have a simple core mechanic. (Basically, use a d20 to determine if you hit, roll damage if you do.)
- Find ways to cheat against that mechanic.
No wonder it took hours to create those perfectly balanced and rule-abiding adventures! 4th Edition's simple design principle was supposed to make it easy, so the poor DM didn't have to spend hours with a calculator. Spells, powers, and exploits were nothing more than simple-to-track ways for the PCs to break the rules on their end--just don't forget to tap your cards!
OD&D is actually built on the same principle. Every spell, every magic item, and every special ability is basically a little cheat against the core mechanic. If you want that ogre to be able to breathe fire once a day, just do it! Don't worry about whether the master weaponsmith has enough levels in "expert" to forge mithril--just declare that he does, and unless there's a compelling reason not to, leave him a 0-level human (dwarf, whatever) for crying out loud!
I remember an apocryphal Conan novel that I read a while back in which the titular barbarian meets a band of montebanks. Among them are a husband and wife team who do knife-throwing tricks; basically, he hurls knives at her and she dodges them at the last possible moment. Now, it's admitted in the novel that neither are warriors per se, but nevertheless their skills surpass those of Conan in their particular areas of expertise.
3rd Edition would have us balancing their stats and giving them levels in fighter and working out feats and in the process giving them a boatload of hit points to the point where they would be superior to normal warriors even in a face-to-face fight--even though the book expressly tells us that they aren't. In OD&D, it's simple: They're still o-level normal humans, but he gets a special +5 (or even a +10--he makes some awesome throws in the book) bonus with thrown weapons, and she gets a special bonus of at least that much to her armor class (so long as she is facing her opponent--in the book, she is knocked out from behind during a pitched battle). You can work out their other stats if you want to--but you don't have to. Just give them a typical monster's stat block, cheat a bit, and go on your merry way.
Those evil cultists don't have to be wizards or clerics: Give them fighting men stats and maybe a few extra bonuses or abilities when they're within their hidden sanctum. You don't have to figure out how many ranks the town guards have in Spot; just decide whether they have received training (are skilled) or not and then throw in whatever bonuses seem appropriate when the thief tries to sneak past them . . . or just give him a target number and have him roll the dice.
Now for the "do it fair" part. You can cheat with the numbers all you want to--as long as you don't change them once battle is joined. If everyone in the party crits on that ogre in the first round and it never even gets a chance to show off its cool fire-breathing ability, don't give it extra hit points just because you're miffed at the players' luck. Especially never do it if it isn't just luck, but also good play that results in the loss of your work.
Of course, you'll have spent less time working, so it won't sting so bad when that happens.