From the sounds of what Bethesda is doing with the new AI the creatures of the worlds will have their own schedule, like wolves hunting and such.
That and also Bethesda was talking about how everything wont "attack you". Like the screen shot in the GI magazine showing the player holding a mace and casting a spell in front of 2 wolves. In the pic, the wolves do not show any hesitation or aggressiveness, just looking on. So let me put it this way, each "enemy" has a personality, so maybe while you are walking to town, you see a troll or a wolf, they may just do a few things:
1)Just look on and go about their business
2) Maybe go for cover as they may be scared of you)
3) are just the aggressive type and may attack you or may defend itself