Outside of fora devoted to individual games, I haven't found a place better suited than theRPGsite to discussion of design and practice within or near "traditional" or "mainstream" RPG paradigms. But there are two things that keep screwing that up. One is, as Tony said, the fact that people see "Theory" and think it's a place to bring in outside grievances and bitch about the Forge. The second is that other people see "Theory" and think it's a place to continue Forge-type discussion. As I said, this makes discussion of actual craft very difficult because the foundational assumptions of "RPGs in general" are just too diverse. It's wearying to have to preface every post with a disclaimer that defines "what is an RPG for the sake of this discussion".
And this is partly why both the "design-by-post" thread ideas I've been kicking around starting have remained quarely in the "idea in my head that occasionally pops up" category The other of course is the usual procrastination.
I want a game design forum WITHOUT the theory. Like Art of Game Design used to be back on RPGnet long ago, but with more actual traffic and people posting to it.
So basically, the threads I've been considering have been held back because I didn't feel there was presently an appropriate place to put them.
I don't give two flaming shits about theory. I think the entire concept of "RPG theory" itself is the most idiotic nonsense I've ever heard. And I don't care to have to step around a bunch of pretentious bullshit just to talk about whether the probability curve of my die mechanic is going to be alright, or whether this particular skill seems to powerful, or whatever.