Strategy is how you win a war. Tactics is what you use to carry out tactics. Strategy is planning. Tactics is execution. In an RTS, rushing or booming are strategies. Tasking your cavalry behind the infantry to attack the artillery is tactics. Strategies change very slowly over the course of history. Tactics change constantly. Tanks require very different tactics than cavalry, but the strategies do not need to be any different.
AOE3 offers plenty of strategy. I think it's our most strategic game. For exampple, choosing which Deck to use has a huge affect on your strategy.
We also wanted to offer more tactics. We wanted to offer players new ways of commanding their cavalry to engage the artillery. We wanted the player to feel more like the leader of the army rather than every single unit on the field. We're still doing that, but in a less ambitious way than we originally set out to do.
We still have formations, and they do more than in AOK. You can still force your Musketeers to fight with bayonets, or put your Halberdiers into Cover mode to shield them from ranged attacks. What we backed off was some of the more controversial formation controls.
Changing formations felt sluggish to some players. They missed the instant responsiveness of issuing a command to their units. Breaking and reforming locked armies was an extra step before a battle that distracted players. Players felt cheated when they failed to optimally wheel a formation in the right direction. Did they deserve to lose the fight? Sure. Were they outplayed? Yep. Was it fun? For too many playtesters, it wasn't. Could we have made it fun eventually? Sure. But there's a lot we wanted to do with this game.
Like Lysimachus and others have vouched, there is a lot to do in a game of AOE3. Having time to execute that kind of tactical control just isn't available. True, we simplified some of the early economic micro to buy room for combat control. But we also filled that space with other features, like the Home City, more buildings, Treasures and Trading Posts. And you still will lose every game if you don't pay attention to combat. This was not the case in AOK where setting a gather point in an enemy town and just spamming units was an effective strategy.
You still have to micromanage your military units. A lot. More so than our previous games. That may disappoint some players, but it just goes with a game that has artillery who are powerful at range but weak hand-to-hand.