If somebody at the table says wouldn’t it be cool if… and I think that yes, it would be cool if… Why not? As a referee I reserve the right veto stuff that is already fixed in my world, and stuff that breaks the mood of the setting, but other than that, I’m fine with player inspiration. This doesn’t happen too often, though, because a large part of the game is about exploration. It only works if there is something in the referee’s head and notes that is there to explore. If players get to make up what they will find, then it isn’t exploration. I like exploration, thus player contribution is mostly limited to “I’m sure there’s a tavern in this town…” and “I’ll go looking for some beggars…” I often improvise details for particular locations, so if these ideas are plausible and entertaining, I run with them.
I realize that here I’m saying that the setting is fixed and ready to be explored and in my Swiss Referee Style Manual I say I prefer starting with a “a small hex map.” The point is that I try to avoid overpreparing. No more than necessary!
Some players like to introduce characters from their backstory. Since I don’t like to read long backstories, and I don’t like to integrate complicated backstories into the game, I prefer there to be a very small number of characters introduced by players, say two or three. A teacher, a contact, a foe, that kind of thing.
The reason I don’t like long backstories is that I think most of them are boring to read, integrating them into the plot is a lot of work, it makes plots depend on the survival of player characters and on the presence of players themselves and finally I prefer to integrate what happens at the table to integrating what people write at home. I want as much as possible to happen at the table because that is what entertains me the most.
Again, during play somebody might say woudln’t it be cool if I met… and just as I said above, I’m not opposed to inspiration and improvisation. What I want to avoid is the baggage that comes with backstories. Players should feel free to write one and keep it to themselves – to help them role-play, to help them improvise, to help them be a better player at the table. All I care about is being entertained at the table. If a backstory helps, please write one. I just don’t want to read it. Show, don’t tell.