
Tieflings have been around a while; there's nothing wrong with a player being able to play one. Putting them in a race chapter in the beginning of the PHB sends the wrong message. It distances the game from the base races that are generic fantasy assumptions now (humans, elves, dwarves, and halflings, principally).
Totally disagree. I see absolutely no need for the default assumption of an option in the book to be that you can't play it.The most important thing is that the books make it perfectly clear that these rare, very rare, and unique races and classes are in no way to be expected to be available for play without the express consent of the DM (or the group as a whole).
Did I say that? I didn't say that. There's a core, which is generic. Then you build on that. If you add fifty elven subraces and high magic, you get FR. If you add warforged and dinosaurs, you get Eberron. If you add tieflings and warlords, you get 4e (or, more specifically, its default setting and style, whatever that's called).Why on earth should D&D be under any obligation to be "generic"? I don't play D&D to be generic, I've got a 9-5 where I play a generic human being who does generic things all day long. Why on earth would I have any desire to have a "generic" fantasy experience? I can rewatch LOTR if I want that. I should think that after some 40 years of existence, D&D has grown beyond "generic".

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.