Racial Ability Scores - Why even the physical ones are bad actually
Disclaimer: While in the headline and certain sections of the text I will use the term "race" and certain derivative words, I will mostly use the term "species" going forward, since that could be the term One D&D will use in the future.
So I was inspired by a video of D&D "hot takes" to write this, because one take presented in that video was that racial ability score bonuses represent reality, especially when looking at physical strength. The argument itself listed the tired example of orcs of course always being stronger than e.g. halflings, but let's examine this a bit further.
First of I'm not going to argue that mental ability score increases tied to species are a good idea. No species is wiser than others, or more charismatic, or whatever. Saying that a species should have a higher mental ability score than others by default is basically just phrenology. Mental capacity is predominantly based on nurture, with genetics playing only a marginal role. By creating a fictional system in which several species have predetermined differences in their baseline intelligence/wisdom/charisma can easily lead to that game mechanic reinforcing beliefs that similar things exist among human ethnic groups. End of story, there are many people smarter than me who have written or said more on this subject.
But the physical argument is also bad actually. For one excercise is a thing that exists, and while yes, certain physical characteristics which are based on genetics do allow for certain people to excel more in certain sports, applying that on a species-wide scale also can reinforce certain notions people have in real life about certain ethnic groups. This applies to all three physical ability scores.
While strength is the obvious one, making presumptions about dexterity and constitution is also bad, especially since the former is the most versatile physical ability score and is connected to two skills, sleight of hand and stealth, that have largely negative connotations.
However, in 5e's current state, there are no playable species that have negative modifiers anymore. Kobolds used to have a -2 in Strength, while orcs used to have a -2 to Intelligence. Otherwise, unless I am forgetting something, only NPC species listed in the DMG ever featured negative ability score modifiers and those basically were always intended as templates to build NPCs around anyway. Otherwise it was always clear that playable species seem to have at most bonuses in a stat. Elves and halflings were more dextrous, dwarves had high constitution, that sort of stuff. And honestly, while I get the argument that e.g. all goliaths should be stronger than gnomes... The game already has mechanics in place which give a more nuanced version of this.
The answer to that is size category and everything that entails! Size impacts the space you occupy, of course, but it also affects your carrying capacity, who you can grapple or shove, and what sorts of weapon you can use.
Grapples and shoves are limited to creatures at most one size category larger than yourself, so small species such as goblins can't grapple creatures larger than medium, aka most playable species. Meanwhile a human can wrestle larger foes, including stuff like horses. Given that one presumes that weight scales according to size, that makes sense and gives a certain degree of basic strength. Now the success chance is then based on the athletics skill, but already knowing that, rules as written, even a 20 strength gnome fighter with proficiency in athletics can't shove a horse says a lot. Mostly about the length of the limbs of the player character but still.
Carrying capacity and weapon usage are more clear-cut. Small and medium-sized creatures can carry a maximum of fifteen-times their strength score. Larger creatures can carry double that, tiny creatures half of that. Now obviously that system is very simple and designed to make players of smaller species not feel like they can carry far less than their medium-sized party members...
But there is a species feature that directly impacts this feature and creates a gradation: Powerful Build. Seen with half-orcs, goliaths, and a few others, it states that you count as one size larger in terms of calculating carrying capacity! Now to a certain extent this exists to also make species that border on being large-sized actually medium-sized while still conveying their actual size, but it also creates a three-tier system! Small creatures, if shrunk down one category, are now tiny and thus are easier to overencumber. Regular mediums can only carry more if enlarged one more size, while power build mediums are already at their peak performance and even if made tiny through intense magical effort they'd still have the carrying capacity of a small/medium creature!
The third aspect is weapon size. Small (and tiny) creatures already can't effectively use weapons that have the heavy property, like the maul, because they have disadvantage on the attacks with those weapons. Now weapons in 5e are presumed to be made for medium-sized creatures, but using the logic of the "Base the Damage on the Weapon" section in the DMG (p.277), if you create a monster using weapons, you increase the number of damage dice by one for each size category based on the original weapon. So a quarterstaff made to be used by a huge creature would deal 3d6/3d8 damage instead of the usual 1d6/1d8. Meanwhile most tiny weapons only deal a singular point of damage, as is evident with the sprite monster whose bow and sword only deal 1 damage each.
Now that means that if the players find a weapon made for a large creature, like an ogre, then I as the DM would probably rule that it is unusable for the small PCs, would only be usable with disadvantage for medium-sized PCs (and be unable to use it if it normally would have the heavy property), and PCs with powerful build could use it normally thanks to that species feature, though they'd be affected by the heavy property if the weapon has it normally. So that ogre's 2d6/2d8 quarterstaff would be a great price for any goliath or orc PC... Unless that poor bugger were dexterity-based!
All three of these aspects are based on mass and size but present different levels of potential and vulnerability. Still, given how versatile and powerful ability scores are in D&D, I'm glad that goblins and kobolds and the like don't have to work harder to hit hard in 5e than half-orcs or dragonborn have to, partially also because just because someone has longer arms or can carry heavier boxes doesn't translate to that person punching better (to me strength as an abiltiy score also always implies knowing how to use it better!). That's also why the many intelligence-based skills are necessary, because otherwise the net cast by these six numbers would be too widely cast if you don't try to add some nuance to that.
Anyway, the TL;DR is that the size category feature and the Powerful Build species feature are more than enough to replace physical ability score modifiers for species since just because someone the size of an adult can carry heavier boxes than someone the size of a kid, that doesn't mean they can always punch harder.
