One of the problems with this is that certain things, such as driving and most other things that the previous writeup referred to as 'automatic' are done considerably worse when thought is devoted to them. Thinking about how you do things in itself distracts from actually doing them.
You can use this principle to beat people skilled in sports if you lose once, then ask them what you did wrong. Chances are, first time around they weren't actually thinking about what they did - it was automatic - but when you ask them how they did it, in the next game they will focus on that and not be able to play well. Don't bet on this though (literally or figuratively) as it most likely doesn't apply to everything, not to mention that most likely the person will be able to return to their normal automatic mode of play in a fairly short time.
Or, take driving. Most people who have been driving for a long period of time, say more than a few years, unconsciously form behaviors and responses to common driving scenarios; person pulls out there, ease on brake now, accelerate again. These responses tend to be very efficient and above all fast - far faster than actual thought about the driving. Almost reflexive; watch anyone driving when someone pulls in front of them and they hit the brake instantly - no pause for thought. While this probably causes a few accidents, it most likely prevents far more.
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That being said, for the most part, I agree with the above writeup - simplicity is better for play.. Just not for driving.