One thing to consider is that the goliaths are becoming giant-kin rather than just "big guy". Due to that, they gain a sorta magical element. The contast then is between dragonborn (very magical), orcs (very mundane) and goliaths (partially both)
It's also worth noting that tieflings, dragonborn and goliaths will be connected to three of the most common monster types: fiends, dragons and giants. Ardlings would have been a fourth (celestial).
I mean, Fantasy Craft still had the best possible initial species layout (and they actually used the word species at the time). Drake (quadrupedal dragons) Dwarf, Elf, Giant, Goblin, Human (25 sub-variant "Talents") Ogre, Orc, Pech (halflings), Rootwalker (tree people) Saurian (lizard people) Unborn (magically animated people, from Frankenstein monsters to Warforged).
Then each one had something 6ish subrace variants represented by 1st-level only species feats, along with some generic ones, like elemental, celestial, draconic heritage and so on. Then later they introduced feats like "Elf-blood" to do your mixed-species characters for all 12 as well.
D&D is obviously shooting for less of a toolkit approach, but I'd love to see that level of customizability. They had a whole 2 page sidebar showing how to represent just about any humanoid fantasy species. They just needed to get the anthros covered, and they'd have had it all.
I'm a big fan of providing an expansive toolkit, with details on including variations like plant+angel combinations. Can be its own self-contained book only expanded on with major demand, allowing them to focus on the stuff they have story for afterward.
While I like what I have heard and read so far about the 1 D&D Dragonborn, I am not really sold on them getting spectral wings made of fire or one of the other damage types. I would like to see the Dragonborn possessing an updated version of this 3e spell:
Flight of the Dragon (pg. 95 of 3e's Spell Compendium)
Transmutation Level: Sorcerer/Wizard 4 Components: V,M Casting Time: 1 Standard Action Range: Personal Target: you Duration: 10 minutes/level
The wing-claw vaporizes in a puff of acrid smoke, and you feel the muscles of your shoulders warm from the eldritch energies coursing within. Great draconian wings unfurl from your shoulders and reach toward the sky.
A powerful pair of wings sprout from your shoulders, granting fly speed of 100 feet (average). You can't carry aloft more than a light load.
For 1 D&D, I would reduce the fly speed down to 30 feet and shorten the duration down to 1 minute. I would also rename the spell, Dragonflight.
I think they just should have started with Aasimar instead of making the Aardlings, and then they really muddied up the concept of the Aardling with the animal thing. Now while they strongly connected the Aasimar with Angels, I felt that was a mistake too. They should have just had 3 celestial legacies of standard 3 spells for a core PHB Aasimar that are counterparts to the 3 common Tiefling legacies, and then said that there are rarer legacies of Aasimar (the ones in Monsters of the Multiverse) out there.
That made me laugh, but as a miniatures collector, I really do find orcs and goliaths way too similar on the tabletop - burly, bald grey dudes. That's why all my orcs are green. Okay, that and years playing Warhammer FB.