I was cleaning yesterday and happened across my copy of WG6 Isle of the Ape by Gary Gygax. I sat down and leafed through it and came across what I see as the largest difference between 1e and 3e.
Starting on page 6 and continuing on page 8 is a massive boxed text soliloquy of Tenser giving the party of 18th level PC's their marching orders. This is a whole pile of text, at a guess, I'm thinking about 1500 words or so. But, that's not my point. Towards the end of the speach is the following text:
Page 8 Isle of the Ape said:
At this, several of the crew begin unfolding a device. YOu recognize it as a folding boat. One of the sailors tells you that the command words are "Jolly", "Dragonship", and "Batten" to cause the magical box to become a boat, ship or box again. You realize that you must remember thse command words if you are to use the craft.
((The boxed text ends here with an interjection by the author))
Note to the DM: Do not allow any notation of these words. Memorization is required.
Stop and think about the implied power there. The module writer assumes that the DM has so much authority at the table that he can dictate to the players that they cannot even write down a vital piece of information. When I was 13 and playing this for the first time, I blithely accepted this as simply true. Now, I read this and think that there isn't a chance that I would do it, either as a DM or as a player.
3e does not assume this level of power on the part of the DM. Nor does it generally consider targeting the player rather than the character as fair game. This goes beyond simple problem solving IMO, this is deliberately setting up the situation so that the DM can say, "AHA GOTCHA" when, three weeks later, the players have forgotten the words to their boat because their minds were so fuzzed over after listening to a ten minute boxed text speech.
Another line caught my eye on the next page:
page 9 said:
As players with high level characters, the participants should show no hesitation about accepting the challenge of the undertaking which is herein proposed. If they do, you should suggest that they are not properly role-playing their characters. Use coercion, flattery, humiliation or whatever else is necessary to bring them around.
Again, this sort of antagonistic approach to DMing has very much changed. The idea that I should humiliate my players into jumping onto my personal adventure has perhaps gone out of style.
Now, I realize that these are rather extreme examples from a single module. And certainly not all were like this. But, some were. This, IMO, really illustrates the difference in edition. Yes, the DM is assumed to have a lot less authority around the table than what's being assumed here.