I don't like that, either. I'm Canadian - should I be required to have proficiency in hockey? (I don't). Languages, maybe, but again there are plenty of exceptions. Describing the typical features of a culture or species makes sense and is useful. Lots of Canadians do love playing hockey, poutine (overrated and sometimes kinda gross), and wearing toques (only if absolutely necessary).
But making cultural traits mandatory is strange to me. It think it is very odd, for example, that all dwarves are given proficiency with axes and hammers, a set of tools, and "stonecutting." Like, it is unthinkable that there could be a nerdy dwarf who wasn't into any of those things? Or who grew up on a farm in the plains taking care of the animals?
Edit: to be clear, I'm not saying it's wrong to have dwarves that mostly dwell underground, are good with hammers and axes, and handy with tools. I just think it's problematic (and boring) to require those traits of the exceptional individuals who are the player characters. Identifying those cultural traits as suggestions for players who want to play into the dwarf stereotype, or elf stereotype, or whatever, is awesome and useful. But a player who wants to say, "Nah, I'm not that kind of dwarf" shouldn't be shut down, IMO. Their choosing a different path doesn't invalidate the cultural trends of the DM's world. Bilbo choosing to go adventuring didn't mean that most hobbits stopped being elevensies-obsessed little NIMBYs.
As with alignment, adding the word "typically" to cultural traits takes nothing away but allows a lot more room for the imagination.