Some people are really getting carried away in this thread;
micro != strategy
micro != tactics
Micromanagement is the act of manually controlling the game through mouse clicks and hotkey presses. Micro in itself is a mechanical act that does not require brain functions, but dexterity.
Obviously you need micro to execute any strategy or tactic, but when supposedly 'casual' gamers in this thread who 'dont understand micro' complain about it, they are referring to circumstances in the heat of battle when the amount of micro required for a perfect execution is overwhelming, and can cause a player with superior strategy and tactics to lose to a player that has superior micro.
Micro advocates like KS and Mokon are blatantly ignoring this, claiming that micro is maneuvers like flanking with cav and pulling out in time. Sorry, almost any decent player can pull that off and it doesn't take much micro. That's not the kind of micro that wins games though. Focus fire, rolling the unit that the opponent is focus firing on, choosing a different unit to focus fire on when your opponent is rolling the unit you were focusing on before and so on. Telling each of your gun cav to stop shooting at a musketeer and shoot at the sword cav next to him that your gun cav counters. Jerking your arty around to 'get the drop' on your opponent's army. Charging with a cheap unit to get the opponent's ranged units to unload then moving your army in range to get the first volley off.
I'm just scratching the surface here, but that's the sort of bullpoopie micro that's often required to win a competitive game and has nothing to do with clever tactics or strategy. It's manual labor.
Oh, and I completely agree with the removal of advanced tactical formations from AOE3 - formations should exist because they are useful in themselves - not because they provide some artificial stat bonus.