I'm all for discussion. I suspect that we discuss our games ahead of time, just like you do. I think that the difference is that when our DM says "I'd like to play a game of heroic PCs in the Forgotten Realms, no evil alignments, no Tieflings because they are devil spawn and I don't want to deal with the NPCs wanting to attack the PCs all of the time", etc., our players just tend to say "Sure, that sounds fun" instead of "Well, why exactly do you want to remove Tieflings?" or "Why do you want to play in the Forgotten Realms?".
It sounds like a trust issue, but maybe it isn't.
Presumably the GM has some reason for proposing the campaign as X rather than Y.
Whatever the nature of that reason is, the players can be motivated by the same sort of reason to want to play character A raher than character B.
There's no reason to think that trust, or lack of trust, is a bigger factor in one case than the other.
What if the players want to play Halflings in a Dragonlance setting? What if they want to play Kender in a Forgotten Realms setting? What is they want to play walking-talking Minotaurs in Karameikos/Mystara? What if they want to play a Warforged in Greyhawk? What I'm getting at is, when one selects a setting to play in, one has chosen it due to the distinct canon, lore, myth, races, geography, personalities, politics...etc.
If I would like to run a political and nationalistic storyline within Karameikos and I make the restriction that I would like all the characters to either be human Traladaran or human Thyatians I should be able to without others calling for 'failure of imagination'
My take on these examples, and on KarinsDad's in the quote above as well, is that the player
isn't choosing a setting based on distinct canon, lore, etc.
I mean, practically by definition a player who wants to play a halfling in Krynn, or a minotaur in Karameikos, isn't committed to the canon of the setting.
So if the GM is very into a setting and its canon, and the player is not, compromise of some sort will probably be required.
Setting is a peculiar thing in RPGing. From
here:
Setting therefore becomes a one-step removed education and appreciation project. There’s a big book about the setting. The GM reads the book. Then, the players enjoy the setting, or rather enjoy the GM’s enjoyment of the setting, by using play as a proxy. As one text puts it, the GM is the lens through which the players see the setting.
There is obviously a very real risk that the players are not going to get the same enjoyment from the setting as the GM. After all, only the GM got to read the book.
From the same author:
Perhaps this is what leads to those monstrous textual setting histories in the books, with the only people who read them (or care) being their authors and the GMs.
If you want to avoid
that outcome, the players need to be dealt in to the setting. There are different wasy to do this, but strong enforcement of PC archetypes won't always be the best way.