I've been asking myself that as well.
A good 'species' needs more than just stat boosts. Because--hot take--species ASIs are more a hinderance than anything else and we should get rid of 'em.
At my table, I noticed the players would immediately gravitate to the Ability Score Increases and sort all of the options into optimal choices for whatever class they wanted to play. If that all-important +2 wasn't in their key ability score, the species was completely off the table--no halfling or gnome barbarians, it's either mountain dwarf or half-orc every single time. It started feeling very repetitive, and my players started joke-complaining about it...so I started letting the players distribute those ability scores however they wished. (This was several years before Tasha's came out.)
The result was a lot more variety in the party's composition. Players started asking themselves "what would a tiefling barbarian look like?" instead of rolling up the same cookie-cutter half-orc with an axe. Variant Human was no longer the most popular choice at the table; I started seeing more dragonborn and firbolgs and aasimar.
So that was the big take-away. Make ASIs flexible/customizable, or remove them from the species traits altogether and just add them at character creation ("Okay guys, roll your stats using the 4d6 method. Then increase one by +2, and a different one by +1"). They're not doing us any favors as-written in the Player's Handbook.