Tying ASIs to Species is completely pointless, because it doesn't actually accomplish what people think it does. It merely gives some people the impression of what it is they think they want.
A +2 to an ability score does not make any creature appreciably more of that thing percentage-wise because of one simple thing-- that stat gets added to a d20 roll. Every test of a person's Dexterity (for example) is not just the ability score modifier... it also include upwards of 20 additional points of d20 roll modifier on top of it.
A person with a 14 Dexterity (+2 mod) has an effective Dexterity for all uses of that ability between 3-22. That's a character's actual Dexterity to do things-- 3-22. And a person with a 12 Dexterity (+1 mod) has an effective Dexterity for all uses of that ability of 2-21. And when we compare those two... we notice all the massive amount of different ways where the "less dexterous" character will easily defeat the supposedly "more dexterous" character in all manner of Dexterity checks. And that will happen all the time.
Which means that the supposed "necessity" of giving elves a +2 ASI to Dexterity (for example) in order to represent an elf's great grace and agility... only provides a 5% boost. That's it. An elf is 5% more graceful and agile than a human (or any other Species). On any check, it's virtually a coin flip as to who's more agile, the elf or someone else. And people think that's actually meaningful? Nope. Not even close. If people are imagining that all elves are lithe Legolas-like creatures-- doing things like flipping upwards onto galloping horses and surfing down staircases... things that no other creatures in the world could possibly do... according to D&D math the dwarf Gimli has merely just a 5% less chance of doing the exact same thing. ASIs and D&D math do not produce the narrative our imaginations think all these Species are meant to have.
One would say that the goliath needs to have a +2 to their Strength score in the Species write-up in order to differentiate it from a tiny halfling? Well... even with that, there's still a pretty easy chance during point-buy character creation that you're going to get a starting halfling in a particular campaign with a +3 STR mod with all their STR-checks rolling between 4-23... while your supposedly "massive" goliath having a +0 STR mod and rolling all their STR-checks between 1-20. Which means that +2 ASI one supposedly needed to have in the Species write-up to really show off the size disparity between goliaths and those tiny halflings has not done jack. All those times where the halfling is rolling 15s, 16s, 18s etc. and the goliath rolls 1s, 2s and 3s... getting absolutely blown out of the water on Strength checks. That ASI bonus due to Species did absolutely nothing to match the math to our narrative expectations and imaginations.
At the end of the day... in order for this game to work as a game it will never create the math situation required to match our expectations in terms of narrative. It can't. Because otherwise the game falls apart. So no one actually needs Species to include ASIs because they just don't accomplish what they want.