I have definitely observed a difference in folks way of thinking between 3e and 4e, with regards to DM empowerment, winging it, etc.
Folks greeted the "Wing it!" philosophy of 4e as if it were some dazzling breakthrough in design.
In a way, it was. 3E is hiding a lot of things in complex calculations.
Hit Dice define BAB and Save Bonuses. Saves are defined by ability scores and Save Bonuses. attacks is defined by ability score bonus + BAB + size.
That's still pretty similar to 4E. But then, there are lots of other modifiers. Monster A has Weapon Focus, Monster B has a magical weapon. Monsters have a natural armor bonus to AC, some also wear armor and magical items.
HD does not define the challenge rating of the monster. HD and INT define skill points, HD define max ranks. Monsters have feats (depending on HD, but sometimes some bonus feats.)
It's like missing the forest for all the trees. There is so much stuff going for which you don't know what the guidelines are or how they come into being. But you think there must be some "grand design" behind, something that makes it all work "perfectly". But since you don't really see what's going on, do you feel you have a chance to improvise things?
Some did. Some noticed that the "Grand Design" behind it is non-existent. That it was the designers guessing that a +7 natural armor bonus sounded fine for a Troll. They didn't even think about what would happen if you gave that Troll a level of Fighter and a Full Plate (though this greatly affects his numbers and the challenge he posed), though they pretended to do so.
But because people believed the Grand Design existed, but couldn't "see" it, they believed that following the arcane rules would probably achieve their goals, and trying something else was bound to fail, because look at how complex this stuff is!
The irony maybe is that just making it up on the stat would have worked well, often even better then strictly following the rules.
The Grand Design in 3E was either not aimed or failed to achieve any balancing goals, and this is typically what people (these days) worried most when using the rules. To use the dreaded GNS terms: The rules were mostly "simulationist", but people treated them as "gamist", assuming it would get you balanced monsters and NPCs.
4E comes and says: Pick a role and a level. These are your relevant modifiers and HPs. Now go crazy and add some powers. Feats? Equipment? Who cares! Write in the stat block, but don't worry with the mods. Skills - take what you want, the modifiers are clear.
It tells you right out what the end results of your math is. it doesn't try to explain how it gets there in "game rules as game world physics" sense, but it certainly tells you what numbers to use and where you can do whatever you want.