What niche do any of the species in 5th edition have now? Since WotC decided to make Tasha's the universal rule, what niche does a halfling have that isn't filled out just as well by a gnome, human, or dragonborn? I'm not anti-halfling (I'm anti-gnome!), I like the little guys, but if they're just us but smaller, what do they bring to the table?
That's a fair point, and all we have to go on is...uh..."Elves are magical and live in the forests....Dwarves mine and live underground...and uh...Lizardmen eat people."
Basically cultural elements are being shunted to Background, and now race is what you look like and primarily mechanical benefits. I have mixed feelings about this.
On the one hand, it's great that not all Dwarves hate Orcs, are Greedy, or are naturally adept at navigating underground. Maybe your Dwarves live on the coasts and are sailors?
On the other hand, excising cultural elements from races...er...species...makes them seem "like humans, but different looking" in many cases. Especially since most fantasy species are just remixed and flanderized versions of Earth cultures.
Maybe the PHB shouldn't have anything but humans, and each setting should have it's own unique species with appropriate cultural mechanics?
Honestly, I can't stand how humans are so generic in D&D, to make the other species stand out more, but given that, in 23 years, WotC hasn't figured out how to come up with any unique human benefits beyond "stuff everyone else gets, but more of it", I doubt that's ever going to change.