So you're saying you're not interested in playing in an established setting. You should just say that.
Not at all actually. If I play in an established setting, I make it a point to make the most established character I can possibly make. AFAIC, what's the point of playing in an established setting and then ignoring that setting to make a character?
However, that being said, I realize that I am very much an outlier here. At least in my experience. Most players barely pay any attention to the setting and come to the table with a character concept already fleshed out in their head that they will then just dump into whatever setting the DM is playing and expect it to work.
And, again, since we're talking about restrictions, if the restriction has no real reason other than "well, they just don't" then, no, that doesn't have a whole lot of meaning to me. So, the fact that there are no gnomes in Scarred Lands doesn't mean that I won't allow players to play a gnome. ((Note, gnomes were added later to the setting in a later supplement on another continent - but the main continent of Ghaelspad has no gnomes.))
Or, the whole orc thing in Dragonlance. As I said there, orcs were not originally left out of the setting. You absolutely could play a half-orc in Dragonlance when it came out. The whole "there are no orcs in this setting" is a later change to the setting that was mostly done to distance the setting from Tolkien rather than for any actual in-universe reason. Considering that orcs in 1e were just another kind of goblin anyway, I fail to see the big deal.
Would I play a half-orc in Dragonlance? Nope. But, then again, the very traditional DL game that I did play in sort of recently featured a gnomish sorcerer and a kender cleric, as well as a minotaur bard. So, well, who am i to judge? It was a great game and having those characters there added, rather than subtracted, from the game.
Like I said earlier, player excitement is worth far, far more to me than any lore written by someone who has never and will never sit at my table.