Rel
Liquid Awesome
Strawman.
Golly, that's a nice attempt to negate my point with one word.
Communication is good. Knowing when to not force communication is just as important.
In short, there is a big difference between you communicating better (good) and you trying to force others to do so (bad).
As any reputable therapist or counselor will tell you!
I wasn't under the impression that the OP was unwilling to discuss his reasoning out of some desire to protect a sensitive emotional subject. I was under the impression that he simply found it an annoying waste of time to have to give his reasons.
I would further posit that it's completely valid for the player to ask, "Why don't you want to discuss it?" Again, I find, "I just don't want to." to be an inferior answer to, "The subject of fantasy metals is one that I'm emotionally uncomfortable with and I'd rather not talk about my reasons for removing them from the game." It is even an inferior answer to, "I don't consider myself as the GM to have any obligation to discuss my reasons for disallowing fantasy metals from my game with the players." If that is the answer then I have just gained very valuable information from the GM that informs me a great deal about what to expect.
And trying to force others to do so is not so that they gain a benefit; it is so that you do. It is both selfish and offensive.
People can (and do) dress that up six ways to Sunday, but in the end, it is what it is, and no rationalization changes it to something different.
I'll dress it up like this: I find this assertion to be wholly incorrect based on my experience. On the few historical occasions where I've found myself pushing somebody for explanations it has been because I wanted to gain understanding to our mutual benefit. It has very possibly been because I felt that the only alternative to gaining that understanding was to end the relationship. And I felt that it was worth it, to both of us, to push them for answers rather than resort to "the door".
If that seems to be an extreme reaction to the situation posed in the OP, it's probably because nobody ever clammed up on me over something as trivial as why they were excluding some element from a roleplaying game.