Not 100% sure it was Dropped Frames, just to be clear. But it is a very interesting/informative interview, so I'd recommend it regardless. I'll need to rewatch it.
I think they could add languages as a low-key thing and just put a description in character creation that says something like "Common is by far the most prevalent language in Faerun, but at rare occasions one might find it useful to know other languages." Or something similar along these lines that would let the player know that it's not terribly important in the game and more of a fluff thing. And then when a player's tiefling comes across writing in Infernal in some cult hideout, the player will feel rewarded: "a-ha! I can read this odd writing in an obscure language - so cool!".