(In movies combatants don't often stand toe-to-toe in one spot repeating the same attacks; They move around and try many different tactics).
Whereas IRL combatants confine themselves to seperate 5 ft squares?
There is hardly anything about 3E combat that is realistic and I'm somewhat baffled as to why someone would think it's a simulator for anything (or prior editions for that matter). The flavor text in 4E is as easily ignored as most of the things that happened in 3E. In 3E my high level fighter can dive head-first off of a 100 ft cliff, and get up the next round and run his full movement rate.
In fact,
> my movement rate never changes unless the terrain does (IRL, people's physical capabilities are not constant)
> damage never affects my strength, dexterity, etc.
> poison affects me if I'm "hit" but not "hit"
> I never make mistakes in judging distances
> I never accidently hit the guy standing next to me with my sword
> I never miscast a spell
> I can actually attack someone first with a dagger when they have a longsword if I "win initiative"
> I can play out my entire combat round while everyone else stands around and watches me
> a typical combat is me standing in one 5 ft square and someone else standing in theirs
> I never drop my weapon unless someone uses some maneuver
> My weapon never breaks unless someone uses a maneuver
> My wounds never get infected unless there's some special magic at work
> I have the same chance of hitting an object with a bow at 10 ft as I have of hitting the same object at 40 ft
And these are some random things that come to mind - I'm sure someone who tried to think about this could come up with a list 10x as long.
I would be really surprised if anyone who hasn't played 3E before picks up the game and says "wow, this is so realistic". There's nothing "realistic" about an adventurer being swallowed over and over by purple worms during his career and yet he's never broken a bone or had to sharpen his sword. What's "realistic" about starting off your career as a 1st level noob, and within a few months you're slaying dragons and diving head-first off of cliffs? How about at getting better at picking locks because you were standing next to a guy that fireballed some orcs? Or you get more powers from your god because you've killed some monsters?
The biggest issue in my opinion, and the one I have mixed feelings about, is the difference between realistic and cinematic combat. It's probably one of the biggest distinctions between 4E and 3E.
IMO there is no realistic combat in 3E. In fact, I have a hard time saying that's even a matter of opinion. As another poster pointed out, DnD combat has always been designed to determine outcome, and the detail of what actually happened during combat was not a priority. 3E introduced 5 ft squares and other details - but I don't see any reason to treat those things differently that saving throws and hit points were treated in prior editions. I seriously would expect that anyone who hadn't played 3E before would laugh at me if I told them that the system were designed to model realistic medieval combat.