"Enough time".Every tree will be a 'great' tree eventually if you give it enough time and proper care. Note I didn't say you have to follow all the 'rules'.
Yeah, sure. Namnhi, I've been practicing bonsai for over 45 years. I wont have another 45 years to redo all the mistakes I made.
The "rules" you rail against are, in part, my lifetime of experience. I freely share them here. You may not appreciate them, you do not have to follow them. I also post photos of my trees where I illustrate the application of the rules, and how they make good bonsai. I have not seen any pictures of your bonsai "without rules". So, I cannot say whether your approach is valid.
I do prefer Classical bonsai styling over the Naturalistic, but that can be considered a matter of taste. But, both schools have common ground. Notice, if you will, on Walter's tree: there are no hanging needles below the pads. Notice too, the tree is more or less "balanced". Both sides of the tree are close to being equally strong. (There are places on both sides that are too thick and need thinning.)
Tasks like "thinning" are not "rules for the sake of rules" they're there because that's how you keep a tree compact and healthy for decades.