kitcik
Adventurer
Well, bear in mind, in all the pre-3e games I played in, we didn't use miniatures, really. (Okay we usually had them, but just used them for marching order and to help visualize what our guys looked like)
So positioning was pretty much all narrative, not done on a grid or anything.
With that said, strictly speaking, 3e didn't introduce attacks of opportunity. In 1st ed AD&D anyway (which is what I've mostly played, probably 60% that/30% BECMI/10% 3e) you would get a free attack if someone disengaged from you in melee. (That was for fleeing though)
And in the DMG, it did indicate that when spellcasters would try to start casting a spell, opponents would try to hit them to interupt.
But again, you couldn't just plow through people.
I mean, really, is a 500 lb ogre really going to be able to bull rush through 2-3 200+lb warriors with heavy armor and very pointy weapons? And why wouldn't the mage be running away from said ogre?
We played the same way.
But, getting to that last point, let's consider the size ratio there. If I, a 200 lb adult man (and assuming I was a warrior), came upon 2-3 80 lb boys protecting another one standing behind them, yes I could bull rush right through them regardless of what they were wearing or carrying.
Not that I played 1E that way - I did it exactly as you said - but just making a point. 500lb is pretty darn big.