If one considers treating monsters as "critters with tactics and their own minds" as
part of presenting a fun challenge for the players, then it all comes together.
I think there's a bit more pressure on the 'encounter' in current D&D, because the designers expect it to take up such a chunk of time. An 'encounter' these days is not so much a possible event in the environment as a set-piece game in itself.
Silverblade the Ench said:
"the whole viewpoint had shifted to playing an RPG has become Kriegspiel"
There are indeed prominent board-game features in 4e. The game gets a lot of mileage out of the square grid and moving pieces on it. The mass of rules built up around that, roughly in the neighborhood of the 3e corpus, is certainly impressive when compared to the basic abstraction of old TSR-D&D (or even old RuneQuest).
On the other hand, the explicit game-mechanical bits and bobs were merely
the starting point of potential considerations in the old mode of play. The fundamental premise was that characters existed in a world no more fully described in the rule-books than is our real world. Give
Amber Diceless a try sometime, if you think it takes a "board game" to get into fine points move by move!