Thank you for answering my questions.
You are welcome.
I think I agree with just about everything else you said, so I didn't quote it here.
The one thing I still don't get is that I understand the above quote as, and I want you to know I'm not intentionally mischaracterizing you, "It's a roleplaying game because it has that name or 'tag'. Call D&D a 'pen and paper game' and it'll be dropped in terms of roleplaying to settlers of catan. Call Catan a 'roleplaying' game and people will step up."
That isn't quite what I intended. The important part is expectations, not the name, and these expectations are set up by a lot more than just the name. Things like tradition (people traditionally roleplay in D&D, but not in settlers of Catan), advice and suggestions set up in game texts (Settlers of Catan's manual has nothing but rules, the PHB and DMG are filled with setting and roleplaying advice), and other forms of communication between people who play such games sets up these expectations.
Basically, people learn how to play the game from other people who play the game, even if those other people are merely the game creators or random people on an internet forum. The more roleplaying is part of a generally accepted way of playing the game (which it certainly is in RPGs, but not necessarily in other kinds of games), then there is so expectation that people playing the game will roleplay.
If you really want to try to wrap your mind around this process, try looking at various games that fall somewhere between RPGs and Chess on the spectrum. In such games, the question of whether roleplaying is generally accepted or not is totally up in the air. MMORPGs are probably the most visible example, where roleplaying may be strongly encouraged and widely practiced in one place, but may be laughed at on a different server in the same game. Single player computer RPGs that let you create your own character, such as Fable or Fallout, also fall in that gray area, though it may be harder to get good information about different ideas of how roleplay in single-player games (and yes, I do believe that roleplaying can exist in a single-player environment).
Basically, roleplaying is part of the social side of gaming, so it is governed by social rules, not mechanical rules.
Now I'll grant you that there's an element of truth to this, but I think it is a small element. In my opinion, different games/systems/editions HAVE to be better/worse for roleplaying. Of course, different people roleplay in different ways (I do get that), but different games result in different effects, I think (so game A might be better for roleplaying for me and game B might be better for my wife, but both games DO impact our roleplaying). Maybe that's not the sole component, or even the main component, but I still can't understand anyone who says "roleplaying is system independent". I'd like to, but I can't get that.
Well, I suppose we will just have to disagree. As I said before, different kinds of games may affect the way some kinds of roleplaying are expressed, but I just don't think a set of rules exist that can either encourage someone to roleplay who doesn't want to, or discourage someone who really wants to.