In fact, I'm pretty sure you can be a game designer without coding much at all (the don't stop tip.) I have pages of unique, different designs and modules that have never been implemented in any live game. I know that they could be translated into code, but there is honeslty no reason for me to do that. I can continue to develop and refine the designs as they exist on paper.

So, I guess my point is that I'd really like to agree with the final point. From my experience as a programmer it is always a much better idea to spend 60-70 % of your development time on planning and the rest on actually implementing it.

But unless you have tons of free time or experient mentors it's always better to read some books and articles the get the basics before jumping into any task. And by the way never assume that just because you can use something well you are qualified to design that something.