A lesson I've learned
Lesson: Simplifying your lists and your life down to its barest of essentials, eliminates the need for complex planning systems. Period.
Not many people realise this despite the fact that they've learnt how to get things done (good thing) they could still do a lot better by making "getting things done" secondary only to "minimalism".
So I've come to realise being productive means two things, in this order of priority:
1. Minimalising, Simplifying, eliminating
2. Getting things done
I tend toward simplicity and agree with what you have said. I do find however that one man's simplicity is another man's complexity. The entirety of GTD is too complex for me, but I retain several key concepts which for me simplify life. An example of this is the A-Z filing system. Ridiculously simple, yet it has saved me more time than almost any other concept in the GTD system. For me paper is a way to be simple, yet others like a device and incorporate it into their system seamlessly.
I see using the GTD process and a means to that exact end. By providing a structure with which to organize ideas and projects, I can more easily eliminate the unnecessary and concentrate on what is truly important. Ahhhhh.
Ideas, for me, are a commodity, but not when they get in the way of living. Here's to zen structure!