If you plan to add racial maximums to the game for the sake of realism, you may want to consider just what is needed to be realistic.
For instance, compare a human and a halfling. Lets assume same "shape", but the human is twice the height. Since volume is the product of three dimensions, and mass is proportional to volume, that means the human is 8 times the mass.
Strength will roughly scale as the cross sectional area of the muscles, which in turn should scale with the square of the height (again, assuming the same shape). That means that a human built identically to a halfling should be 4 times as strong. A +2 advantage for the human relative to the halfling isn't anywhere close to large enough!
Quickness of movement (ie. dexterity) should scale as strength/mass, so the halfling gets an advantage of a factor of 2 here. Factor of 2, not +2.
I submit that the structure of D&D simply does not allow this difference to be realistically contained within the rules in a fun way. For similar reasons there are no rules to support sexual dimorphism. After all, it is supremely silly to go after a dragon with a sword for ANY humanoid, and yet we pretend that this is OKAY within the context of the game. If a human male can do it, why not a halfling or a human female. The scale of that deed is already absurd enough that it is silly to try to draw distinctions between the various tiny (compared to dragon) creatures that will encounter it.
But we're not aiming for 100% realism when we (I) say that there should be racial ASIs, maximum/minimums, and/or impactful racial characteristics. All that stuff you mentioned is more detail than is necessary. There's a happy middle ground between "all races are similar enough so we'll give them the same stats" and "every race's exact biology is painstakingly calculated to give precise bonuses and penalties."
Also, you are making assumptions here that halflings are built the same as a human, just smaller. They're a fantasy race - they could very well have denser (or entirely different) muscles than humans, and thus easily more than 1/4 as strong as a human.
The structure of D&D is fairly flexible and allows for a lot, and should make sense at a broad level, but it's just as obviously fantasy: not a 100% accurate physics simulator. Giving a +1 or +2 bonus to an ability score is more than enough in my mind to reflect racial differences without getting into the complex, nitty-gritty details of biology and physics. Don't let the perfect be the enemy of the good.
