Except that campaign settings are not core rules. They are optional settings. So again you have no point.
First, I just want to say I completely get what you are saying here. And why your replies look the way they do. I think people are misunderstanding you possibly due to how you are saying this. I'll elaborate below.
No they're not. Orcs are filthy, chaotic freebooters. Klingons are an advanced, honorable warrior race.
Unrelated to previous (or later) quotes: Hate to disagree with you but this one I actually see. Same with Vulcans = Elves. Yes, it is a
major refluff and you don't have "orcs" anymore. But yeah, Klingons = Orcs I perfectly see.
Anyone else see Goblins = Ferengi?
The problem is - everything you're saying doesn't belong in D&D has been in D&D for 30+ years, already.
I think it has to do with HOW they have been in DnD. Whether or not they're core to the game, if they should be included just because they existed or have been used at some point isn't much of a reason to include it by default in the game.
So in order ... (1)
Expedition to the Barrier Peaks goes back to 1980. Crashed spaceship, laser guns, etc. (2) gelatinous cubes and the like go back to the very first campaigns, mid-70's. (3) Monks were put into D&D specifically because one of the players liked the Destroyer novels; they've been a part ever since. (4) Again, goes back to the mid-70's. (5) The robot sub is the Apparatus of Kwalish; check your 1e DMG.
1 - Adventures, not the game as a whole. I would wager the mini-balrog is too. Single adventure or specific setting only. Not applied generally across ALL games, or even regularly outside the one adventure. Sometimes never seen again but you say it is part of the history of DnD? Also, how often are these spaceships and things in the core rules; PHB, DMG, MM kinds of books?
2 - Monster, which has shown up in several MM's to my knowledge. This one is pretty safe as DnD for me, and even by tim's logic (assuming I understand correctly). However, the justification you are using is "campaigns". By that logic Sun Elves belong in the core books because they go back many many years. Or Kender too. I'm not suggesting (at all) that these things should be cut from the game as a whole, I doubt their existence as "core" whatever that truly means.
3 - Monks, again, have been in DnD a long time and even in "core" books so I think you lost me.
4 - I don't know what (4) is referring to actually. But I'd be remiss if I excluded it, I'm sure.
5 - Also, DMG.. not the greatest source but again I'd accept it. That is a book, generally speaking part of the "core" and if it has been around since 1e then I think it should be for 5e. Since when do we use the existence of one object to automatically include anything related to it (genre or not). Dragons have been around forever, how about
half-dragons (wait, I don't know if they have been too.. ermmm..) everything in the 3e Dragon Magic book? Is that all core now?
How in the world can you say stuff that was in D&D back in the first decade isn't a part of D&D?
I missed the beginning of this conversation so please excuse my ignorance (but I'm assuming the answer has evolved too, as the discussion has). In what way is tim saying things aren't "part of DnD" as you put it? I assumed he meant in the core books, that's what I wrote this predicated upon. Or that players should be able to demand to play these kinds of things, instead of them being campaign, setting or adventure dependent. If not, if it is just these things being included somewhere or anywhere in DnD... then yeah, DnD has had some pretty messed up stuff happening over the years. Magic of Incarnum would be my go to example. I found MoI to be odd. Too odd to put into my games, does that mean that it isn't part of DnD? No, but it does mean it is something I don't really care if it gets reprinted for 5e or ever seen again. It is a secondary book, something extra. Something similar to those examples you gave that showed up in early adventures but never seen again. Who cares if it exists, it isn't all that useful to the wider game. That's my only point here, I suppose.