Yeah, think it is a reasonably straightforward "Pick a choice and stick with it, because we're not assuming other options allowing it to be picked will exist."
Master of Fire and Darkness feat is currently broken if that's not how it gets looked at if a Drow picked Cloud of Darkness and then wanted Darkfire too. And that feat was errata'd to deal with the problems of them having errata'd Drow to only get to pick one.