But, hang on here. The 1e DMG is pretty clear on the adversarial role the DM should be playing. There's numerous places where it flat out states that the DM should be against the players. Look at the section on finding secret doors. Or listening at doors for that matter. The rules and the modules are pretty clear that the DM is in an adversarial role.
By some modern standards, I probably do have a somewhat adversarial style. But its not on 100% of the time. Why?
Because, like every other GM, I use or toss rules as I saw fit, based on what I felt the campaign needed. AD&D weapon speed rules? BLECH! Even Gygax talked about D&D rules he didn't use and/or bent into pretzels- they're guidelines, not immutable rules of the universe.
(Though once a rule is used a certain way, that is the way it was used thereafter. One must be consistent.)
So, if it wasn't transparency, then what turned you off of 4e? And, why couldn't you do the same thing with 4e that you did with every other edition - ie. drift the rules so that it fit with your playstyle?
Second question first:
1) because the rules I changed in other editions were much easier to excise...were less crucial...than the aspects of 4Ed I dislike. Like the aforementioned weapon speed rules. That's an easy toss. But the way HPs & HSs work? That's a lot of work to redo.
2) because there were fewer rules I disliked in prior editions compared to 4Ed.
So, what turned us off?
4Ed turned me (and several guys in our group) off out of the starting gate, and only after a while of playing it did I find my personal sweet spot of enjoyment in it...but it remains my least favorite incarnation of the game.
The first problem was the difference in the race/class design tossed out the option of campaign continuity. Our group easily upgraded our game from 1st to 2nd, and the 3Ed conversion guide made that changeover pretty easy. With 4Ed, that wasn't an option- developers even said as much during Pre-release comments- the multiclass rules alone invalidated a good 70% of my PCs.
The second problem was in the combat system. All those modifiers that can pop up, changing from round to round, turn to turn; marking, etc., were pegged early on as being fiddly bits that would slow things down. And they have proven to be so.
Worse, in prior editions, the majority of such modifiers came from one source- spellcasters. That meant, in a typical combat, between 3-5 sources, from friendlies and enemies. In 4Ed, every PC and NPC in the game can buff, debuff & rebuff one or multiple targets every time they act. This slows things down and often results in modifiers getting missed or forgotten.
(Some of the guys in our group are rabid computer gamers, and we even include professional computer game designers among our number.
To a man, this was something they said they would rather have computers tracking.)
Hit Points & Healing Surges: at the very least, there are too many. And their potency is occasionally jarring, seemingly arbitrarily assigned when they run contra to the usual D&D style. Between his HP & HS, my Warlock has more HP than any other PC except the Fighter: this pure caster is tougher than some of the front line fighters. Worse, the Rogue- a striker who actually DOES see melee combat regularly- has maybe 70% of the one who can usually sit back an lob spells. That's ass-backwards.
The alignment system: I personally liked the 9 point system, and that alignment had an actual impact on the game. What 4Ed has is neither complete nor relevant- it may have well been excised completely instead of wasting the space it took up in the books. Even a simple Good/Unaligned/Evil system would have been better, if the alignment had an impact.
I could go on, but I won't.
Like I said, I do enjoy playing 4Ed...but I'll never run it as a DM.