Zardnaar
Legend
Yeah, there may be reasons to say no. I get that. But there are also reasons to say yes.
I think that a lot of the time, people say no out of reflex, but if they paused for a moment and gave it some thought, maybe there’d not just be a way to say yes, but that it may lead to something interesting.
Like the hidden menace race idea you mention.....maybe it was drow, but a PC wanted to be a drow. Now, they could easily be from some other drow culture, but maybe it’s already been established that there’s only one drow culture in this world. But then the DM thinks....what if the hidden menace race isn’t the drow, but is instead some new enemy? And maybe they’re in the underdark and they’re so horrible, drow are fleeing to the surface. And then the campaign has a hidden enemy that the players actually aren’t familiar with and the player gets what he wants.
Depends on how much work you've put into it.
If you've mapped out a Drow city, written up an adventure, NPCs list etc.