If you wish to play Dungeons & Dragons strictly as a board game and don't care about the fiction that is generated by the playing, that's fine. But that is not in any way how Wizards of the Coast sees this game. Everything in this game is designed with story in mind... that's why all these numbers have these fantasy nouns and adjectives on top of them... to create a story out of their use. Thus for them (and a lot of us)... "outside the fiction" is is a phrase that might as well not even exist, because the entire point of playing an RPG as opposed to a board game is to create a fiction. This is why we name our D&D character but don't name our train developer "identity" when playing Ticket To Ride. Because they are two different types of games.I don't care what the character identifies as. If your halfling PC wants to identify as bugbear, go for it. That's between the PC and the game world. Outside of the fiction, though, your "half-elf" is pure human or pure elf.
You may not like that WotC cares more about focusing on fiction rather than mechanics in many places within D&D... and that's fine, you don't have to. But if you want "outside the fiction"-first emphasis in your RPG... waiting on the D&D design department to give it to you means you might sometimes be waiting a long time for it or might not even ever get it.