I feel that, with few exceptions, the best RPG products released since the beginning of the hobby have their origins in actual play by their designers. They may not be slavish, one-to-one reproductions of what the designer and his players did when they used it in play, but they're nevertheless heavily informed by what they did.
So, here's the question: if you discovered beforehand that a given product was something its designer had never played, would that affect your interest in it? Do you think it's important that game designers use their own products or do you think it's possible to design a good game or game product without the designer's personal investment in it? (Note: I'm not talking about a lack of playtesting so much as the idea of a product's being created for reasons other than immediate personal interest by its designer, if that distinction makes sense)
I'm off for the day, as usual. See you tomorrow.