In One D&D, some dated ideas are being dropped, including racial essentialism and the pernicious real world idea that even a drop of "impure" blood fundamentally changes a person. Eric's Grandma wouldn't want us to go down that rabbit hole, but if you're unfamiliar with this, look up "octoroon" on Wikipedia and be, I hope, a little shocked at an attitude that was still around at least as recently as 1974.
So while half-orcs and half-elves aren't their own special categories any more, One D&D walks back in the door with a related idea that I don't think anyone was asking for:
Certain cultures, by default, are associated with certain jobs in D&D. I don't think you'd see a modern ruleset try to codify a similar argument.
If you haven't read the One D&D Character Origins UA yet (and it seems that plenty of YouTubers haven't, for instance, although that doesn't stop them from making 45 minute videos expressing their opinions about it), every one of the new backgrounds includes a bonus language.
The new PHB is going to say these are just examples and players should be making custom backgrounds. But let's be honest, that's an option already, and most players just go with the example ones. So what WotC puts in the examples matters, both as a model and because probably most players will use them and never make a custom background of their own.
Some of the languages seem like reasonable expectations for most worlds. Entertainers all know Elvish, which suggests that the elves have created great works of music and drama that other peoples will either perform verbatim or learn so they can adapt them to their native cultures. Urchins know Common sign language (a new default language added to the list, which is a nice change that I approve of, especially as it carries with it the real world reality that not every deaf person uses the same sign language), which I guess they're using to communicate on the street -- which is takes sign language to a little bit of a weird place, but OK. Acolytes know Celestial, which feels a bit limited (do the Lawful Neutral gods really write their holy books in the language of the upper planes?), but I can see what they're going for.
But Criminals all know Thieves Cant, which feels like a pretty significant element, historically, being handed out a little too freely. (I know people will tell me that Thieves Cant never comes up in their game, but I use it all the time, including just recently when a group playing through Empire of the Ghouls made a wrong turn in the sewers and stumbled into thieves guild territory, shrugging and ignoring the cant signs painted on the walls. I use this PDF
from the DMs Guild, and it's served me well in the often rogue-heavy games I run.) And notably, they're not giving out the other class language, Druidic, as part of a background.
Why does every guide speak Giant? Every pilgrim speaks Halfling? Every sailor can speak Primordial? These feel like big setting decisions and some of them turn ordinary zero level characters (remember, the background is what happens to them before they start adventuring) into something mythic. A sailor being able to speak to magical sea creatures in their own language belongs on Odysseus' ship, not on some random fishing trawler.
And then it starts to get a bit icky. Every charlatan knows Infernal, which suggests unpleasant things about my gnome illusionist. Every gladiator speaks Orcish, which -- despite them walking back previously problematic descriptions of orcs in the Character Races section, makes a strong contrary statement here.
What's more, this feels unnecessary. If groups aren't using languages "enough" for WotC, that's those groups' call. (I make language pretty important in my games, but we're now reaching the level in my main campaign where magic will make it never an issue again.) Under the current rules, anyone can learn additional languages during downtime, so they don't need them handed out willy-nilly at character creation.
This is just a beta test, but this is a decision that should be rolled back. If you agree, please consider including this in your feedback in September.