Wow. Housecats, rose-colored glasses, nostalgia. This thread has just about every erroneous polemical cliche in the basher's book.
Rather than point at 3E and 4E as being corporate pablum aimed at robotic consumers of McFun (which is not necessarily true but would counterbalance the insulting cliches)... let me point out the actual difference. It's the same difference that Mearls pointed out vis a vis 4E versus OD&D.
In old school play you challenge the player, not the character. In new school play, puzzles, riddles, tricks, traps and all the meat of exploration are solved by high dice rolls. Suspicious room? Search check. Dodgy NPC? Sense Motive check. Cryptic inscription? Knowledge Whatever check. In old school play, rather than rolling dice for those things you give your gray matter a go.
That's why in new school gaming, combat comes to the fore so much. Since *all* conflicts are resolved by rolling dice and hoping you roll well (and have leet bonuses), there's very little difference between searching the wizard's lab and stabbing an orc: you roll 1d20 and try to get a high roll, and if you roll low you may be in for some damage. Exploration just becomes another occasion for dice rolling, but a less fun one than combat. So why care about it? Bring on the orcs.
In old school gaming, you didn't even get many XP for fighting. Most of it comes from getting away with the loot. Rather than the trap being just another monster (new school), in old school the monster is just another trap: an encounter which if you mishandle it could be deadly, but is ultimately just an obstacle in the way of acquiring the dingus.
I think you hit the differences very well. I would go one thing further and say combat in 3E and 4E is the one situation where the "gray matter" still counts for the most - since it's not just rolling dice, it is decided for what to roll the dice - do I attack the Hobgoblin Fighter or try to grapple the Goblin Shaman? Do I cast Fireball or is Scorching Burst enough? Do I try to heal the Fighter or do I cast Divine Favor?
Outside of combat, the "decision trees" are far shorter. You don't have to worry about deciding stuff like "Do I search the area to the altar first, or do I search the chest first?" In most cases, these decisions just don't matter.
There might be ways to combine "die roll"-solutions with gray matter - for example, if you had only 3 search rolls per day (only relevant for "difficult" searches), you'd have to decide if you really want to spend two of them on this room (maybe finding some nice treasure), or reserve your dice rolls for later (maybe the Orc Chiefs private "sanctum"?).
(To bring up my favorite example for everything that is good in gaming: Torg does this in a way. Sure, you can always roll skill checks, but if they really count, you might want to spend one of your precious possibilities or a drama card to improve the result. You are way more likely to succeed this way. Of course, you might need this possibility or card in a later scene...)
The interesting question might be - why did we exchange gray-matter for skill rolls? Who is to fault for that?
A lot has been thought about GNS, and I suppose I can do this again here.
It is not really "gamist" to just have a single dice roll for it, if we assume gamisn is about the players dealing with challenges. Because they aren't, they are just rolling dice. There is no strategy involved.
So, was it our desire for "simulation" or believability? The game system had to model this skill, because after all, we are not really in that scene, right? It's our character, and he has the skills, not you.
Maybe the error began when stuff like Int, Wis or Cha became attributes (which, IIRC, was always the case). If my character has an intelligence value, anything requiring intelligence should be governed by that value, not my own intelligence. Otherwise, I am not playing my character!
Of course, there are also "gameplay" reasons to do this - without game rules, you will need to rely on social contract, personal player vs player and player vs DM relationships to have the game work. You might face a DM that doesn't like your solutions, and only allows one way to success. So if you do not explicitly say: "I look below the vase", you will never get the hint you needed. The Gray Matter is cool stuff, but not all people use it equally. A DM can "challenge" his players by being smarter then them, but he can also challenge them by being dumber.
So, in the end, I suppose there are no perfect solutions. I think games and game subsystems that support a kind of "resource management" work best, because this creates less dependency on reading the DMs or the module writers mind, and likewise makes it easier for the DM to find ways to challenge his players. But that's not a perfect solution, and never will be - if your fun is figuring out if an NPC is lying by thinking through what he has said and done, neither rolling a Sense Motive Check (no resource management) or casting a Detect Thought spells (resource management) will be satisfying.
One more not, on "boring Fighters". Fighters are far more intersting in old D&D where you didn't have feats. Why? Because when you have feats in the game, the cool stunt which the feat governs can only be done by someone with the feat. "Tightrope Fighter" feat introduced? Now only people with the feat can do it. "Fast Draw Knife from Teeth" feat? Now only people with that feat can do that move. Each feat that is introduced limits and constricts what is possible for a character to do.
Perhaps people are too brainwashed by 3E+, and when they see a 1E Fighter with no feats they assume that means he cannot do anything. Wrong! That means he can do everything.
Yes, it might be a "brainwash" effect, and it was definitely a flaw I saw in 3E - once you had a feat for some ability previously undefined, you
needed that feat to pull it off.
But did you? Why not do it the 1E way? Why not allow: "Sure, I'll allow this, if you tell me how do to this?" Maybe with a penalty (or is the demand of the DM to be "convinced" by the player already penalty enough?), but why not? If it's in the rules, it is possible and must be done using the rules, if it's not in the rules, it is impossible and you must create rules.
I suppose that famous page 42 in the 4E DMG is an attempt to "fix" the believe that you can only do what is explicily in the rules by - ironically? - giving you rules to adjudicate it.